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PHP Overview: A Beginner’s Guide to Syntax

PHP is a versatile server-side language widely used in web development. Its straightforward syntax makes it suitable for both beginners and advanced developers. In this guide, we will explore the basic syntax of PHP. PHP scripts can be embedded within HTML using special PHP tags.

Basic PHP Syntax

PHP code is executed between PHP tags. The most commonly used tags are <?php ... ?>, which mark the beginning and end of PHP code. This is known as Escaping to PHP.

<?php
    // PHP code goes here
?>

These tags, also known as Canonical PHP tags, indicate to the PHP parser which parts of the document to process. Everything outside these tags is treated as plain HTML. Each PHP command must end with a semicolon (;).

PHP Syntax Example

<?php
    // Using echo to display a message
    echo "Greetings from PHP!";
?>

Output:

Greetings from PHP!

Imagick::adaptiveBlurImage()
Description: Add an adaptive blur filter to the image.
Example:

$image->adaptiveBlurImage(5, 3);
// Output: (applies an adaptive blur with specified radius and sigma)

Imagick::adaptiveResizeImage()
Description: Resize the image according to specific dimensions.
Example:

$image->adaptiveResizeImage(200, 300);
// Output: (resizes image to 200x300 pixels)

Imagick::adaptiveSharpenImage()
Description: Sharpen an image adaptively based on intensity.
Example:

$image->adaptiveThresholdImage(3, 3, 1);
// Output: (applies adaptive threshold for localized pixel intensity control)

Imagick::adaptiveThresholdImage()
Description: Applies a threshold based on local intensity values.
Example:

$image->adaptiveThresholdImage(3, 3, 1);
// Output: (applies adaptive threshold for localized pixel intensity control)

Imagick::addImage()
Description: Add a new image to the Imagick object image list.
Example:

$image->addImage($newImage);
// Output: (adds $newImage to the Imagick list)

Imagick::addNoiseImage()
Description: Add noise to the image for texture or effect.
Example:

$image->addNoiseImage(Imagick::NOISE_IMPULSE);
// Output: (applies impulse noise effect)

Imagick::annotateImage()
Description: Add text annotation to the image.
Example:

$combinedImage = $image->appendImages(true);
// Output: (appends images vertically)

Imagick::appendImages()
Description: Append multiple images vertically or horizontally.
Example:

Single-line comment example!

Imagick::autoLevelImage()
Description: Automatically adjust image levels.
Example:

$image->autoLevelImage();
// Output: (adjusts levels for better brightness and contrast)

Imagick::blackThresholdImage()
Description: Convert pixels below a threshold to black.
Example:

$image->blackThresholdImage('#222222');
// Output: (sets pixels darker than the color threshold to black)

Imagick::blueShiftImage()
Description: Applies a moonlit or nighttime effect.
Example:

$image->blueShiftImage(1.5);
// Output: (adds a blue shift effect with specified intensity)

Imagick::blurImage()
Description: Apply a basic blur effect to the image.
Example:

$image->blurImage(5, 3);
// Output: (adds blur with specified radius and sigma)

Imagick::borderImage()
Description: Add a border to the image.
Example:

$image->borderImage('black', 5, 5);
// Output: (adds a 5-pixel black border)

Imagick::brightnessContrastImage()
Description: Adjust brightness and contrast of the image.
Example:

$image->brightnessContrastImage(20, 30);
// Output: (adjusts brightness by 20 and contrast by 30)

Imagick::charcoalImage()
Description: Simulate a charcoal sketch effect.
Example:

$image->charcoalImage(1, 2);
// Output: (applies charcoal effect)

Imagick::chopImage()
Description: Crop and trim a specific region of the image.
Example:

$image->chopImage(100, 100, 50, 50);
// Output: (removes 100x100 area at specified position)

Imagick::commentImage()
Description: Add a comment to the image.
Example:

$image->commentImage("Sample Comment");
// Output: (adds 'Sample Comment' metadata to the image)

Imagick::convolveImage()
Description: Apply a custom convolution kernel to the image.
Example:

$image->convolveImage(array(1, 2, 1, 2, 4, 2, 1, 2, 1));
// Output: (applies the specified convolution filter)

Imagick::cropImage()
Description: Crop the image to a specified region.
Example:

$image->cropImage(100, 100, 10, 10);
// Output: (crops 100x100 pixels starting from (10, 10))

Imagick::despeckleImage()
Description: Reduce speckle noise in the image.
Example:

$image->despeckleImage();
// Output: (applies despeckle filter to reduce noise)

Imagick::displayImage()
Description: Display the image object.
Example:

$image->displayImage();
// Output: (opens image in default viewer, if available)

Imagick::distortImage()
Description: Distort an image using specific distortion methods.
Example:

$image->distortImage(Imagick::DISTORTION_PERSPECTIVE, array(0,0, 30,60, 120,60, 150,120), true);
// Output: (applies perspective distortion)

Imagick::edgeImage()
Description: Enhance the edges within the image.
Example:

$image->edgeImage(1);
// Output: (enhances edges with specified radius)

Imagick::embossImage()
Description: Apply a grayscale emboss effect.
Example:

$image->embossImage(1, 1);
// Output: (adds emboss effect)

Imagick::enhanceImage()
Description: Improve the quality of a noisy image.
Example:

$image->enhanceImage();
// Output: (enhances image by reducing noise)

Imagick::equalizeImage()
Description: Equalize the histogram of the image.
Example:

$image->equalizeImage();
// Output: (equalizes the image contrast)

Imagick::extentImage()
Description: Set the size and origin of the image.
Example:

$image->extentImage(200, 200, -10, -10);
// Output: (resizes image with new origin offset)

Imagick::flattenImages()
Description: Merge the sequence of images into one.
Example:

$flattenedImage = $image->flattenImages();
// Output: (flattens multiple layers into a single image)

Imagick::flipImage()
Description: Create a vertically flipped image.
Example:

$image->flipImage();
// Output: (flips the image vertically)

Imagick::flopImage()
Description: Create a horizontally flipped image
Example:

$image->flopImage();
// Output: (flips the image horizontally)

Imagick::gammaImage()
Description: Apply gamma correction to the image.
Example:

$image->gammaImage(1.2);
// Output: (adjusts gamma to 1.2)

Imagick::getCopyright()
Description: Return ImageMagick API copyright.
Example:

echo $image->getCopyright();
// Output: (displays ImageMagick copyright)

Imagick::getImageBluePrimary()
Description: Get the chromaticity blue primary point.
Example:

print_r($image->getImageBluePrimary());
// Output: (displays x, y values for blue primary)

Imagick::getImageColors()
Description: Get the number of unique colors in the image.
Example:

echo $image->getImageColors();
// Output: (number of unique colors)

Imagick::getImageColorspace()
Description: Get the colorspace of the image.
Example:

echo $image->getImageColorspace();
// Output: (colorspace type)

Imagick::getImageChannelDepth()
Description: Get the depth of a specific image channel.
Example:

echo $image->getImageChannelDepth(Imagick::CHANNEL_RED);
// Output: (depth of the red channel)

Imagick::getImageDepth()
Description: Get the image depth.
Example:

echo $image->getImageDepth();
// Output: (bit-depth of the image)

Imagick::getImageFormat()
Description: Get the format of the image.
Example:

echo $image->getImageFormat();
// Output: (file format, e.g., PNG)

Imagick::getImageGeometry()
Description: Get width and height of the image.
Example:

print_r($image->getImageGeometry());
// Output: (width and height as an associative array)

Imagick::getImageHeight()
Description: Get the height of the image.
Example:

echo $image->getImageHeight();
// Output: (height in pixels)

Imagick::getImageWidth()
Description: Get the width of the image.
Example:

echo $image->getImageWidth();
// Output: (width in pixels)

Imagick::haldClutImage()
Description: Replace colors in the image using a Hald lookup table.
Example:

$image->haldClutImage($clutImage);
// Output: (replaces colors based on Hald lookup table)

Imagick::identifyImage()
Description: Identify an image and return its attributes.
Example:

print_r($image->identifyImage());
// Output: (image metadata and attributes)

Imagick::magnifyImage()
Description: Scale the image up by 2x.
Example:

$image->magnifyImage();
// Output: (image size increased by 2x)

Imagick::modulateImage()
Description: Adjust brightness, saturation, and hue.
Example:

$image->modulateImage(100, 150, 100);
// Output: (adjusts brightness, saturation, and hue)

Imagick::motionBlurImage()
Description: Simulate motion blur in the image.
Example:

$image->motionBlurImage(5, 10, 45);
// Output: (applies motion blur with specified angle)

Imagick::negateImage()
Description: Invert the colors of the image.
Example:

$image->negateImage(false);
// Output: (inverts colors)

Imagick::newImage()
Description: Create a new image.
Example:

$image->newImage(200, 200, new ImagickPixel('red'));
// Output: (creates a 200x200 red image)

Imagick::normalizeImage()
Description: Enhance the contrast by adjusting colors to span the full color range.
Example:

$image->normalizeImage();
// Output: (adjusts contrast across colors)

Imagick::oilPaintImage()
Description: Simulate an oil painting effect.
Example:

$image->oilPaintImage(3);
// Output: (applies oil paint effect with radius 3)

Imagick::orderedPosterizeImage()
Description: Apply ordered dithering for posterization.
Example:

$image->orderedPosterizeImage("o8x8");
// Output: (reduces colors using dithering)

Imagick::posterizeImage()
Description: Reduce image colors to limited levels.
Example:

$image->posterizeImage(4, false);
// Output: (reduces color levels to 4)

Imagick::queryFonts()
Description: Get the list of available fonts.
Example:

print_r($image->queryFonts());
// Output: (array of font names)

Imagick::radialBlurImage()
Description: Apply radial blur to the image.
Example:

$image->radialBlurImage(5);
// Output: (adds radial blur with 5 degrees)

Imagick::raiseImage()
Description: Create a 3D button effect by lightening edges.
Example:

$image->raiseImage(10, 10, 5, 5, true);
// Output: (creates raised edge effect)

Imagick::randomThresholdImage()
Description: Change pixel values based on intensity.
Example:

$image->randomThresholdImage(0.4 * Imagick::getQuantum(), 0.8 * Imagick::getQuantum());
// Output: (adjusts pixel values based on intensity threshold)

Imagick::readImageBlob()
Description: Read an image from a binary string.
Example:

$image->readImageBlob(file_get_contents("path/to/image.png"));
// Output: (loads image from binary data)

Imagick::recolorImage()
Description: Apply color transformations.
Example:

$image->recolorImage(array(
    1.5, 0, 0,
    0, 1.2, 0,
    0, 0, 1.3
));
// Output: (adjusts RGB color intensities)

Imagick::reduceNoiseImage()
Description: Reduce noise in an image.
Example:

$image->reduceNoiseImage(1);
// Output: (smooths contours and reduces noise)

Imagick::resampleImage()
Description: Resample the image to a desired resolution.
Example:

$image->resampleImage(150, 150, Imagick::FILTER_LANCZOS, 1);
// Output: (resamples to 150x150 dpi)

Imagick::rollImage()
Description: Roll image pixels horizontally and vertically.
Example:

$image->rollImage(10, 10);
// Output: (shifts image by 10 pixels horizontally and vertically)

Imagick::rotationalBlurImage()
Description: Apply rotational blur at a given angle.
Example:

$image->rotationalBlurImage(10);
// Output: (applies 10-degree rotational blur)

Imagick::rotateImage()
Description: Rotate the image by a specified angle.
Example:

$image->rotateImage(new ImagickPixel('white'), 45);
// Output: (rotates image by 45 degrees, filling gaps with white)

Imagick::textureImage()
Description: Tile a texture over the image.
Example:

$image->textureImage($textureImage);
// Output: (tiles $textureImage as a background)

Imagick::thumbnailImage()
Description: Resize the image to thumbnail dimensions.
Example:

$image->thumbnailImage(100, 100);
// Output: (creates 100x100 thumbnail)

Imagick::thresholdImage()
Description: Change pixel values based on threshold.
Example:

$image->thresholdImage(0.5 * Imagick::getQuantum());
// Output: (pixels below threshold set to black, others white)

Imagick::transformImage()
Description: Crop and resize the image according to geometry.
Example:

$image->transformImage("100x100", "200x200");
// Output: (crops to 100x100 and resizes to 200x200)

Imagick::transformImageColorspace()
Description: Convert the image to a different colorspace.
Example:

$image->transformImageColorspace(Imagick::COLORSPACE_GRAY);
// Output: (converts image to grayscale)

Imagick::transposeImage()
Description: Create a vertically mirrored image.
Example:

$image->transposeImage();
// Output: (vertical mirror effect)

Imagick::transverseImage()
Description: Create a horizontally mirrored image.
Example:

$image->transverseImage();
// Output: (horizontal mirror effect)

Imagick::trimImage()
Description: Trim edges of the image.
Example:

$image->trimImage(0);
// Output: (trims edges with matching colors)

Imagick::setImageChannelDepth()
Description: Set channel depth for a specific channel.
Example:

$image->setImageChannelDepth(Imagick::CHANNEL_RED, 16);
// Output: (sets red channel depth to 16 bits)

Imagick::setImageOpacity()
Description: Set the opacity level of the image.
Example:

$image->setImageOpacity(0.5);
// Output: (sets opacity to 50%)

Imagick::sharpenImage()
Description: Sharpen the image with a radius and sigma.
Example:

$image->sharpenImage(2, 1);
// Output: (sharpens with 2 radius and 1 sigma)

Imagick::shaveImage()
Description: Shave pixels off edges of the image.
Example:

$image->shaveImage(10, 10);
// Output: (removes 10 pixels from each edge)

Imagick::shearImage()
Description: Apply a shear transformation to the image.
Example:

$image->shearImage(new ImagickPixel('white'), 20, 30);
// Output: (shears image by 20x30 degrees)

Imagick::sketchImage()
Description: Simulate a pencil sketch effect.
Example:

$image->sketchImage(10, 1, 45);
// Output: (applies sketch effect with given radius, sigma, and angle)

Imagick::solarizeImage()
Description: Apply a solarizing effect.
Example:

$image->solarizeImage(128);
// Output: (solarizes using a threshold of 128)

Imagick::spliceImage()
Description: Splice a solid color into the image.
Example:

$image->spliceImage(10, 10, 5, 5);
// Output: (adds a 10x10 section at coordinates 5,5)

Imagick::spreadImage()
Description: Randomly displace each pixel in a block.
Example:

$image->spreadImage(5);
// Output: (randomly displaces pixels with a 5-pixel radius)

Imagick::unsharpMaskImage()
Description: Apply an unsharp mask filter.
Example:

$image->unsharpMaskImage(1, 0.5, 1, 0.05);
// Output: (sharpens image with unsharp mask)

Imagick::uniqueImageColors()
Description: Discard duplicate colors in the image.
Example:

$image->uniqueImageColors();
// Output: (removes duplicated colors)

Imagick::vignetteImage()
Description: Add a vignette effect to the image.
Example:

$image->vignetteImage(10, 20, 5, 5);
// Output: (adds vignette with given parameters)

Imagick::waveImage()
Description: Apply a wave filter to the image.
Example:

$image->waveImage(5, 50);
// Output: (creates a wave effect with amplitude 5, wavelength 50)

Imagick::whiteThresholdImage()
Description: Set pixels above threshold to white.
Example:

$image->whiteThresholdImage(new ImagickPixel('rgb(200, 200, 200)'));
// Output: (pixels above threshold become white)

Imagick::whiteThresholdImage()
Description: Set pixels above threshold to white.
Example:

$image->whiteThresholdImage(new ImagickPixel('rgb(200, 200, 200)'));
// Output: (pixels above threshold become white)

Imagick::waveImage()
Description: Apply a wave filter to the image.
Example:

$image->waveImage(5, 50);
// Output: (creates a wave effect with amplitude 5, wavelength 50)

Imagick::writeImage()
Description: Write the image to a file.
Example:

$image->writeImage("output.png");
// Output: (saves image to output.png)

Imagick::getImageWidth()
Description: Retrieve the width of the image.
Example:

echo $image->getImageWidth();
// Output: (width of $image)

Imagick::getImageHeight()
Description: Retrieve the height of the image.
Example:

echo $image->getImageHeight();
// Output: (height of $image)

Imagick::getImageFormat()
Description: Retrieve the format of the image.
Example:

echo $image->getImageFormat();
// Output: (format of $image, e.g., PNG, JPEG)

Imagick::getImageResolution()
Description: Get the resolution of the image.
Example:

print_r($image->getImageResolution());
// Output: (image resolution as [x, y] array)

Imagick::setImageUnits()
Description: Set the units of resolution for the image.
Example:

$image->setImageUnits(imagick::RESOLUTION_PIXELSPERINCH);
// Output: (sets resolution units to pixels per inch)

Imagick::shadeImage()
Description: Apply a 3D effect to the image by shading.
Example:

$image->shadeImage(true, 30, 30);
// Output: (adds 3D shading effect)

Image processing and GD functions enable the creation and manipulation of image files across various formats, such as GIF, PNG, JPEG, WBMP, and XPM. With PHP, these functions can directly output the image to the browser. The GD library is central to implementing image functions for this purpose, though other libraries may be needed depending on the image formats involved.

Example: This demonstrates the use of the imagecolorclosesthwb() function in PHP.

<?php

// Create a new image from a given URL
$image = imagecreatefromgif(
'https://www.example.com/sample-image.gif');

// Display the index of the color closest to the specified hue, white, and blackness
echo 'Hue, White, and Blackness closest color index: '
	. imagecolorclosesthwb($image, 120, 200, 50);

imagedestroy($image);
?>

Output:

Hue, White, and Blackness closest color index: 42

The list of Image processing and GD s are given below:

gd_info()

Description: Retrieve information about the installed GD library.

Example:

print_r(gd_info());
// Output: (array of GD library information)

getimagesize()

Description: Get the dimensions of an image.

Example:

$size = getimagesize("example.jpg");
print_r($size);
// Output: (displays array with width, height, and more details)

getimagesizefromstring()

Description: Determine the size of an image from a binary string.

Example:

$imageData = file_get_contents("example.jpg");
$size = getimagesizefromstring($imageData);
print_r($size);
// Output: (array of image size information)

imagealphablending()

Description: Set the blending mode for an image.

Example:

$image = imagecreatetruecolor(200, 200);
imagealphablending($image, true);
// Output: (enables or disables blending for $image)

imagearc()

Description: Create an arc centered at the specified coordinates.

Example:

$image = imagecreatetruecolor(200, 200);
imagearc($image, 100, 100, 150, 150, 0, 180, 0xFFFFFF);
// Output: (draws a half-circle in the image)

imagechar()

Description: Draw a character horizontally on an image.

Example:

imagechar($image, 5, 50, 50, "A", 0xFFFFFF);
// Output: (draws 'A' at (50, 50) on $image)

imagecharup()

Description: Draw a character vertically on an image.

Example:

imagecharup($image, 5, 50, 50, "B", 0xFFFFFF);
// Output: (draws 'B' vertically at (50, 50) on $image)

imagecolorallocate()

Description: Set a color in an image.

Example:

$color = imagecolorallocate($image, 0, 128, 255);
// Output: (assigns a blue color to $image)

imagecolorallocatealpha()

Description: Allocate color with alpha for transparency.

Example:

$color = imagecolorallocatealpha($image, 255, 0, 0, 50);
// Output: (assigns a semi-transparent red color)

imagecolorat()

Description: Get the color of a specific pixel.

Example:

$color = imagecolorat($image, 10, 10);
echo $color;
// Output: (color index of pixel at (10, 10))

imagecolorclosest()

Description: Find the closest color index in the image.

Example:

$color = imagecolorclosest($image, 100, 100, 200);
echo $color;
// Output: (closest color index for the specified RGB)

imagecolorclosestalpha()

Description: Get the closest color with an alpha value.

Example:

$color = imagecolorclosestalpha($image, 100, 100, 200, 50);
echo $color;
// Output: (closest color index with alpha)

imagecolorclosesthwb()

Description: Find the hue, white, and black closest color index.

Example:

$color = imagecolorclosesthwb($image, 255, 0, 0);
echo $color;
// Output: (closest index for hue, white, and black)

imagecolorexact()

Description: Get the index of a specific color in the image palette.

Example:

$color = imagecolorexact($image, 255, 255, 255);
echo $color;
// Output: (color index of exact match for white)

imagecolormatch()

Description: Match the palette version colors of an image to a true-color version.

Example:

imagecolormatch($image1, $image2);
// Output: (matches colors of $image1 to $image2)

imagecolorresolve()

Description: Get the specified color or closest possible in the palette.

Example:

$color = imagecolorresolve($image, 255, 100, 50);
echo $color;
// Output: (index of exact or nearest color)

imagecolorresolvealpha()

Description: Find specified color and alpha value or closest alternative.

Example:

$color = imagecolorresolvealpha($image, 255, 100, 50, 50);
echo $color;
// Output: (index of color with alpha)

imagecolorset()

Description: Set the color for a specified palette index.

Example:

imagecolorset($image, 5, 100, 50, 150);
// Output: (sets color at index 5 in palette)

imagecolorsforindex()

Description: Get the colors at a specified index.

Example:

$color = imagecolorsforindex($image, 5);
print_r($color);
// Output: (RGB array of colors at index 5)

imagecolorstotal()

Description: Find the number of colors in an image’s palette.

Example:

echo imagecolorstotal($image);
// Output: (total number of colors in the palette)

imagecolortransparent()

Description: Define a color as transparent in the image.

Example:

imagecolortransparent($image, $color);
// Output: (sets $color as transparent)

imageconvolution()

Description: Apply a convolution matrix to the image.

Example:

$matrix = array(
  array(0, -1, 0),
  array(-1, 4, -1),
  array(0, -1, 0)
);
imageconvolution($image, $matrix, 1, 127);
// Output: (applies convolution effect)

imagecopy()

Description: Copy all or part of an image.

Example:

imagecopy($image, $src, 0, 0, 0, 0, 100, 100);
// Output: (copies $src onto $image)

imagecopymerge()

Description: Copy and merge an image with transparency.

Example:

imagecopymerge($image, $src, 0, 0, 0, 0, 100, 100, 50);
// Output: (merges $src onto $image with 50% opacity)

imagecopymergegray()

Description: Merge a grayscale version of part of an image.

Example:

echo IntlChar::isspace(" ");
// Output: 1

imagecreate()

Description: Create a new palette-based image.

Example:

$image = imagecreate(200, 200);
// Output: (creates 200x200 image with color palette)

imagecreatetruecolor()

Description: Create a new true-color image.

Example:

$image = imagecreatetruecolor(200, 200);
// Output: (creates 200x200 true-color image)

imagecrop()

Description: Crop the image to a specified rectangle.

Example:

$image = imagecrop($image, array("x"=>50, "y"=>50, "width"=>100, "height"=>100));
// Output: (crops $image to the given dimensions)

imagedashedline()

Description: Draw a dashed line in the image.

Example:

imagedashedline($image, 0, 0, 200, 200, 0xFFFFFF);
// Output: (draws dashed line from (0, 0) to (200, 200))

imagefilledarc()

Description: Draw a filled partial arc.

Example:

imagefilledarc($image, 100, 100, 100, 100, 0, 180, 0x0000FF, IMG_ARC_PIE);
// Output: (draws a half-circle arc filled in blue)

imagefilledrectangle()

Description: Draw a filled rectangle.

Example:

imagefilledrectangle($image, 0, 0, 100, 50, 0x000000);
// Output: (draws black rectangle at specified area)

imagefilledarc()

Description: Draw a filled partial arc.

Example:

imagefilledarc($image, 100, 100, 100, 100, 0, 180, 0x0000FF, IMG_ARC_PIE);
// Output: (draws a half-circle arc filled in blue)

imagelayereffect()

Description: Set alpha blending flag for layering effects.

Example:

imagelayereffect($image, IMG_EFFECT_OVERLAY);
// Output: (enables overlay effect on $image)

imagepolygon()

Description: Draw a polygon on the image.

Example:

$points = array(50, 0, 100, 100, 0, 100);
imagepolygon($image, $points, 3, 0xFFFFFF);
// Output: (draws white triangle)

imagerectangle()

Description: Draw a rectangle in the image.

Example:

imagerectangle($image, 10, 10, 100, 50, 0xFF0000);
// Output: (draws red rectangle at specified area)

imagetruecolortopalette()

Description: Convert a true-color image to a palette image.

Example:

imagetruecolortopalette($image, false, 256);
// Output: (converts image to 256 color palette)

imagesy()

Description: Return the height of an image.

Example:

echo imagesy($image);
// Output: (height of $image)

imagesx()

Description: Return the width of an image.

Example:

echo imagesx($image);
// Output: (width of $image)

The IntlChar class in PHP provides a set of static methods for character processing, conforming to the Unicode standard.

IntlChar::charAge(): Get the Unicode version in which the code point was first designated.

IntlChar::charAge(int $codepoint): array;

IntlChar::charDigitValue(): Get the decimal digit value of a code point.

IntlChar::charDigitValue(int $codepoint): int;

IntlChar::charDirection(): Get the bidirectional category value for a code point.

IntlChar::charDirection(int $codepoint): int;

IntlChar::charFromName(): Find a Unicode character by its name.

IntlChar::charFromName(string $name, int $nameChoice = IntlChar::UNICODE_CHAR_NAME): int;

IntlChar::charMirror(): Get the “mirror image” of a code point.

IntlChar::charMirror(int $codepoint): int;

IntlChar::charName(): Get the Unicode name for a code point.

IntlChar::charName(int $codepoint, int $nameChoice = IntlChar::UNICODE_CHAR_NAME): string;

IntlChar::charScript(): Get the script value for a code point.

IntlChar::charScript(int $codepoint): int;

IntlChar::charType(): Get the general category value for a code point.

IntlChar::charType(int $codepoint): int;

IntlChar::digit(): Get the decimal digit value of a numeric code point.

disk_free_space($directory);

IntlChar::enumCharNames(): Enumerate all assigned Unicode character names.

IntlChar::enumCharNames(int $start, int $end, callable $callback, int $nameChoice = IntlChar::UNICODE_CHAR_NAME);

IntlChar::enumCharTypes(): Enumerate all code points with the same general category.

IntlChar::enumCharTypes(callable $callback);

IntlChar::foldCase(): Perform Unicode simple case folding.

IntlChar::foldCase(int $codepoint, int $options = IntlChar::FOLD_CASE_DEFAULT): int;

IntlChar::forDigit(): Get the numeric value of a Unicode digit.

IntlChar::forDigit(int $digit, int $radix = 10): int;

IntlChar::getBidiPairedBracket(): Get the paired bracket character for a code point.

IntlChar::getBidiPairedBracket(int $codepoint): int;

IntlChar::getBlockCode(): Get the Unicode block value for a code point.

IntlChar::getBlockCode(int $codepoint): int;

IntlChar::getCombiningClass(): Get the combining class value for a code point.

IntlChar::getCombiningClass(int $codepoint): int;

IntlChar::getFC_NFKC_Closure(): Get the FC_NFKC_Closure property value for a code point.

IntlChar::getFC_NFKC_Closure(int $codepoint): string;

IntlChar::getIntPropertyMaxValue(): Get the maximum value for a Unicode property.

IntlChar::getIntPropertyMaxValue(int $property): int;

IntlChar::getIntPropertyMinValue(): Get the minimum value for a Unicode property.

IntlChar::getIntPropertyMinValue(int $property): int;

IntlChar::getIntPropertyValue(): Get the integer value for a Unicode property.

IntlChar::getIntPropertyValue(int $codepoint, int $property): int;

IntlChar::getNumericValue(): Get the numeric value for a code point.

IntlChar::getNumericValue(int $codepoint): float;

IntlChar::getPropertyEnum(): Get the integer value for a property alias.

IntlChar::getPropertyEnum(string $alias): int;

IntlChar::getPropertyName(): Get the property name for a property value.

IntlChar::getPropertyName(int $property, int $nameChoice = IntlChar::LONG_PROPERTY_NAME): string;

IntlChar::getPropertyValueName(): Get the name for a property value.

IntlChar::getPropertyValueName(int $property, int $value, int $nameChoice = IntlChar::LONG_PROPERTY_NAME): string;

IntlChar::getUnicodeVersion(): Get the Unicode version.

IntlChar::getUnicodeVersion(): array;

IntlChar::hasBinaryProperty(): Check if a code point has a binary property.

IntlChar::hasBinaryProperty(int $codepoint, int $property): bool;

IntlChar::hasBinaryProperty(): Check if a code point has a binary property.

IntlChar::hasBinaryProperty(int $codepoint, int $property): bool;

IntlChar::isalnum(): Check if a code point is an alphanumeric character.

IntlChar::isalnum(int $codepoint): bool;

IntlChar::isalpha(): Check if a code point is an alphabetic character.

IntlChar::isalpha(int $codepoint): bool;

IntlChar::isbase(): Check if a code point is a base character.

IntlChar::isbase(int $codepoint): bool;

IntlChar::isblank(): Check if a code point is a blank character.

IntlChar::isblank(int $codepoint): bool;

IntlChar::iscntrl(): Check if a code point is a control character.

IntlChar::iscntrl(int $codepoint): bool;

IntlChar::isdefined(): Check if a code point is a defined character.

IntlChar::isdefined(int $codepoint): bool;

IntlChar::isdigit(): Check if a code point is a digit character.

IntlChar::isdigit(int $codepoint): bool;

fileowner($filename);

fileowner($filename);

IntlChar::isgraph(): Check if a code point is a graphic character.

IntlChar::isgraph(int $codepoint): bool;

IntlChar::isgraph(int $codepoint): bool;

IntlChar::isgraph(int $codepoint): bool;

IntlChar::isIDIgnorable(): Check if a code point is an ignorable character.

IntlChar::isIDIgnorable(int $codepoint): bool;

IntlChar::isIDPart(): Check if a code point can be part of an identifier.

IntlChar::isIDPart(int $codepoint): bool;

fnmatch(): Matches a filename or string against a specified pattern.

fnmatch($pattern, $string, $flags);

IntlChar::isIDStart(): Check if a code point can start an identifier.

IntlChar::isIDStart(int $codepoint): bool;

IntlChar::isISOControl(): Check if a code point is an ISO control character.

IntlChar::isISOControl(int $codepoint): bool;

IntlChar::islower(): Check if a code point is a lowercase character.

IntlChar::islower(int $codepoint): bool;

IntlChar::islower(int $codepoint): bool

IntlChar::islower(int $codepoint): bool;

IntlChar::isMirrored(): Check if a code point has the Bidi_Mirrored property.

IntlChar::isMirrored(int $codepoint): bool;

IntlChar::isprint(): Check if a code point is a printable character.

fseek($handle, $offset, $whence);

IntlChar::ispunct(): Check if a code point is a punctuation character.

IntlChar::ispunct(int $codepoint): bool;

IntlChar::isspace(): Check if a code point is a space character.

IntlChar::isspace(int $codepoint): bool;

IntlChar::isUWhiteSpace(): Check if a code point has the White_Space property.

IntlChar::isUWhiteSpace(int $codepoint): bool;

The intl extension in PHP provides capabilities for internationalization (i18n) and localization (l10n), supporting features like locale-aware formatting, transliteration, and message formatting. Below is a list of key functions provided by the intl extension.

Collator

1. collator_asort(): Sort array maintaining index association.

collator_asort(Collator $coll, array &$arr, int $sort_flag = Collator::SORT_REGULAR): bool;

chgrp(): Changes the group ownership of a file.

chgrp($filename, $group);

collator_compare(): Compare two Unicode strings.

collator_compare(Collator $coll, string $str1, string $str2): int;

collator_get_attribute(): Get an attribute value.

collator_get_attribute(Collator $coll, int $attr): int|false;

collator_get_error_code(): Get collator’s last error code.

collator_get_error_code(Collator $coll): int;

collator_get_error_message(): Get text for collator’s last error code.

collator_get_error_message(Collator $coll): string;

collator_get_locale(): Get the locale name of the collator.

collator_get_locale(Collator $coll, int $type): string|false;

collator_get_sort_key(): Get sorting key for a string.

collator_get_sort_key(Collator $coll, string $string): string|false;

collator_get_strength(): Get the collator’s strength.

collator_get_strength(Collator $coll): int;

collator_set_attribute(): Set an attribute value.

collator_set_attribute(Collator $coll, int $attr, int $val): bool;

collator_set_strength(): Set the collator’s strength.

collator_set_strength(Collator $coll, int $strength): bool;

collator_sort(): Sort an array.

collator_sort(Collator $coll, array &$arr, int $sort_flag = Collator::SORT_REGULAR): bool;

collator_sort_with_sort_keys(): Sort array using specified sort keys.

collator_sort_with_sort_keys(Collator $coll, array &$arr): bool;

NumberFormatter

numfmt_create(): Create a number formatter.

numfmt_create(string $locale, int $style, ?string $pattern = null): ?NumberFormatter;

numfmt_format(): Format a number.

numfmt_format(NumberFormatter $fmt, int|float $num, int $type = NumberFormatter::TYPE_DEFAULT): string|false;

numfmt_format_currency(): Format a currency value.

numfmt_format_currency(NumberFormatter $fmt, float $value, string $currency): string|false;

numfmt_get_attribute(): Get an attribute value.

fgetcsv($handle, $length, $delimiter, $enclosure, $escape);

fgets(): Gets a line from a file pointer.

numfmt_get_attribute(NumberFormatter $fmt, int $attr): int|float|false;

numfmt_get_error_code(): Get formatter’s last error code.

numfmt_get_error_code(NumberFormatter $fmt): int;

numfmt_get_error_message(): Get text for formatter’s last error code.

numfmt_get_error_message(NumberFormatter $fmt): string;

numfmt_get_locale(): Get the locale name of the formatter.

numfmt_get_locale(NumberFormatter $fmt, int $type): string|false;

numfmt_get_pattern(): Get formatter pattern.

file_exists($filename);

numfmt_get_symbol(): Get a symbol value.

numfmt_get_symbol(NumberFormatter $fmt, int $attr): string|false;

numfmt_get_text_attribute(): Get a text attribute value.

numfmt_get_text_attribute(NumberFormatter $fmt, int $attr): string|false;

numfmt_parse(): Parse a number.

numfmt_parse(NumberFormatter $fmt, string $value, int $type = NumberFormatter::TYPE_DOUBLE, &$position = null): int|float|false;

numfmt_parse_currency(): Parse a currency number.

numfmt_parse_currency(NumberFormatter $fmt, string $value, string &$currency, &$position = null): float|false;

numfmt_set_attribute(): Set an attribute value.

numfmt_set_attribute(NumberFormatter $fmt, int $attr, int|float $value): bool;

numfmt_set_pattern(): Set formatter pattern.

numfmt_set_pattern(NumberFormatter $fmt, string $pattern): bool;

numfmt_set_symbol(): Set a symbol value.

numfmt_set_symbol(NumberFormatter $fmt, int $attr, string $value): bool;

MessageFormatter

msgfmt_create(): Create a message formatter.

msgfmt_create(string $locale, string $pattern): ?MessageFormatter;

msgfmt_format(): Format the message.

msgfmt_format(MessageFormatter $fmt, array $args): string|false;

msgfmt_format_message(): Quick format message.

msgfmt_format_message(string $locale, string $pattern, array $args): string|false;

msgfmt_get_error_code(): Get formatter’s last error code.

msgfmt_get_error_code(MessageFormatter $fmt): int;

msgfmt_get_error_message(): Get text for formatter’s last error code.

msgfmt_get_error_message(MessageFormatter $fmt): string;

msgfmt_get_locale(): Get the locale name of the formatter.

msgfmt_get_locale(MessageFormatter $fmt): string|false;

msgfmt_get_locale(MessageFormatter $fmt): string|false;

msgfmt_get_locale(MessageFormatter $fmt): string|false;

msgfmt_get_pattern(): Get formatter pattern.

msgfmt_get_pattern(MessageFormatter $fmt): string|false;

msgfmt_parse(): Parse input string.

msgfmt_parse(MessageFormatter $fmt, string $value): array|false;

msgfmt_parse_message(): Quick parse input string.

msgfmt_parse_message(string $locale, string $pattern, string $source): array|false;

msgfmt_set_pattern(): Set formatter pattern.

msgfmt_set_pattern(MessageFormatter $fmt, string $pattern): bool;

Normalizer

normalizer_is_normalized(): Checks if the provided string is already in the specified normalization form.

normalizer_is_normalized(string $input, int $form = Normalizer::FORM_C): bool;

normalizer_normalize(): Normalizes the input provided and returns the normalized string.

normalizer_normalize(string $input, int $form = Normalizer::FORM_C): string|false;

ResourceBundle

resourcebundle_create(): Create a resource bundle.

resourcebundle_create(string $locale, string $bundlename, bool $fallback): ?ResourceBundle;

resourcebundle_count(): Get the number of elements in the bundle.

resourcebundle_count(ResourceBundle $bundle): int;

resourcebundle_get(): Get data from the bundle.

resourcebundle_get(ResourceBundle $bundle, int|string $index): mixed;

resourcebundle_get_error_message(): Get text for bundle’s last error code.

resourcebundle_get_error_message(ResourceBundle $bundle): string;

resourcebundle_get_error_code(): Get bundle’s last error code.

resourcebundle_get_error_code(ResourceBundle $bundle): int;

resourcebundle_locales(): Get supported locales.

resourcebundle_locales(string $bundlename): array|false;

basename()
Description: Return the filename from a given path.
Example:

echo basename("/path/to/file.txt");
// Output: file.txt

chgrp()
Description: Change the user group of a specified file.
Example:

chgrp("example.txt", "users");
// Output: (changes the group to 'users')

chmod()
Description: Modify file permissions to a specified mode.
Example:

chmod("example.txt", 0755);
// Output: (sets permissions to 755)

chown()
Description: Assign a new owner to a specified file.
Example:

chown("example.txt", "newowner");
// Output: (changes the owner to 'newowner')

copy()
Description: Create a copy of a specified file.
Example:

copy("source.txt", "copy.txt");
// Output: (creates a duplicate of 'source.txt' as 'copy.txt')

dirname()
Description: Get the directory path from a file path.
Example:

echo dirname("/path/to/file.txt");
// Output: /path/to

disk_free_space()
Description: Determine the free space in a specified directory.
Example:

echo disk_free_space("/");
// Output: (returns free space in bytes)

disk_total_space()
Description: Retrieve the total storage capacity of a specified directory.
Example:

echo disk_total_space("/");
// Output: (returns total space in bytes)

fclose()
Description: Close a file pointer that is currently open.
Example:

$file = fopen("example.txt", "r");
fclose($file);
// Output: (closes 'example.txt')

feof()
Description: Check if the end-of-file has been reached on a file pointer.
Example:

$file = fopen("example.txt", "r");
while (!feof($file)) {
    echo fgets($file);
}
fclose($file);
// Output: (reads until end of file)

fflush()
Description: Flush the output buffer to an open file.
Example:

$file = fopen("example.txt", "a");
fwrite($file, "New content");
fflush($file);
fclose($file);
// Output: (writes 'New content' and flushes buffer)

fgetc()
Description: Retrieve a single character from an open file.
Example:

$file = fopen("example.csv", "w");
fputcsv($file, ["Name", "Age", "City"]); // Writes CSV line
fclose($file);

fgets()
Description: Read a line from a file pointer.
Example:

$file = fopen("example.txt", "r");
echo fgets($file);
fclose($file);
// Output: (reads and outputs the first line)

fgetss()
Description: Read a line from a file while stripping out HTML and PHP tags.
Example:

$file = fopen("example.txt", "r");
echo fgetss($file);
fclose($file);
// Output: (outputs the line without HTML tags)

file_exists()
Description: Check if a file or directory exists.
Example:

echo file_exists("example.txt") ? "Exists" : "Does not exist";
// Output: Exists or Does not exist

file_get_contents()
Description: Read the entire file content into a string.
Example:

echo file_get_contents("example.txt");
// Output: (displays file contents as a string)

file_put_contents()
Description: Write a string to a file.
Example:

file_put_contents("example.txt", "Some content");
// Output: (writes 'Some content' to 'example.txt')

fileatime()
Description: Retrieve the last access time of a specified file.
Example:

echo date("F d Y H:i:s", fileatime("example.txt"));
// Output: (displays last access date and time)

filesize()
Description: Get the size of a specified file in bytes.
Example:

echo filesize("example.txt");
// Output: (file size in bytes)

filectime()
Description: Get the last change time of a specified file.
Example:

echo date("F d Y H:i:s", filectime("example.txt"));
// Output: (displays last change date and time)

filemtime()
Description:Return the last modified time of a specified file.
Example:

echo date("F d Y H:i:s", filemtime("example.txt"));
// Output: (displays last modified date and time)

fileperms()
Description: Retrieve the permissions for a file or directory.
Example:

echo substr(sprintf('%o', fileperms("example.txt")), -4);
// Output: (displays permissions, e.g., 0755)

filesize()
Description: Get the size of a specified file in bytes.
Example:

echo filesize("example.txt");
// Output: (file size in bytes)

filetype()
Description: Determine the type of file.
Example:

echo filetype("example.txt");
// Output: file or dir

flock()
Description: Apply a portable advisory lock on the file.
Example:

$file = fopen("example.txt", "r+");
if (flock($file, LOCK_EX)) {
    // Do something
    flock($file, LOCK_UN);
}
fclose($file);
// Output: (locks and unlocks the file)

fopen()
Description: Open a file or URL.
Example:

$file = fopen("example.txt", "r");
// Output: (opens 'example.txt' for reading)

fpassthru()
Description: Output all remaining data from a file pointer until EOF.
Example:

The variable is an integer.
The variable is a string.

fputcsv()
Description: Write a line of CSV formatted data to a file.
Example:

$file = fopen("data.csv", "w");
fputcsv($file, ["Name", "Age"]);
fclose($file);
// Output: (writes "Name, Age" to 'data.csv')

fread()
Description: Read up to a specified length of bytes from a file.
Example:

$file = fopen("example.txt", "r");
echo fread($file, 100);
fclose($file);
// Output: (displays first 100 bytes)

fseek()
Description: Set the file pointer to a specified position.
Example:

$file = fopen("example.txt", "r");
fseek($file, 5);
echo fgets($file);
fclose($file);
// Output: (displays content starting from position 5)

fstat()
Description: Return information about an open file.
Example:

$file = fopen("example.txt", "r");
print_r(fstat($file));
fclose($file);
// Output: (displays file info array)

ftell()
Description: Get the current position of the file pointer.
Example:

$file = fopen("example.txt", "r");
echo ftell($file);
fclose($file);
// Output: (current file pointer position)

ftruncate()
Description: Truncate a file to a specified length.
Example:

$file = fopen("example.txt", "r+");
ftruncate($file, 50);
fclose($file);
// Output: (shortens file to 50 bytes)

fwrite()
Description: Write a string to a file.
Example:

$file = fopen("example.txt", "w");
fwrite($file, "PHP Filesystem Functions");
fclose($file);
// Output: (writes text to 'example.txt')

is_dir()
Description: Check if a path is a directory.
Example:

echo is_dir("/path/to/directory") ? "Directory" : "Not a directory";
// Output: Directory or Not a directory

is_executable()
Description: Determine if a file is executable.
Example:

echo is_executable("script.sh") ? "Executable" : "Not executable";
// Output: Executable or Not executable

is_file()
Description: Verify if a path is a regular file.
Example:

echo is_file("example.txt") ? "File" : "Not a file";
// Output: File or Not a file

is_link()
Description: Check if a specified file is a symbolic link.
Example:

echo is_link("example_link") ? "Symbolic link" : "Not a symbolic link";
// Output: Symbolic link or Not a symbolic link

is_readable()
Description: Determine if a file exists and is readable.
Example:

echo is_readable("example.txt") ? "Readable" : "Not readable";
// Output: Readable or Not readable

is_uploaded_file()
Description: Check if a file was uploaded via HTTP POST.
Example:

echo is_uploaded_file($_FILES['file']['tmp_name']) ? "Uploaded" : "Not uploaded";
// Output: Uploaded or Not uploaded

is_writable()
Description: Verify if a file is writable.
Example:

echo is_writable("example.txt") ? "Writable" : "Not writable";
// Output: Writable or Not writable

link()
Description: Create a hard link for a specified target.
Example:

link("target.txt", "hardlink.txt");
// Output: (creates a hard link 'hardlink.txt' pointing to 'target.txt')

lstat()
Description: Retrieve information about a file or symbolic link.
Example:

print_r(lstat("example.txt"));
// Output: (array of file or symbolic link information)

popen()
Description: Open a pipe to a specified command.
Example:

$pipe = popen("ls", "r");
// Output: (opens a pipe to list directory contents)

pclose()
Description: Close a pipe opened by popen().
Example:

$pipe = popen("ls", "r");
pclose($pipe);
// Output: (closes the pipe to the command 'ls')

pathinfo()
Description: Get information about a path as an associative array or string.
Example:

print_r(pathinfo("example.txt"));
// Output: (displays path info, e.g., directory, basename, extension)

readfile()
Description: Read a file and output it directly to the buffer.
Example:

readfile("example.txt");
// Output: (displays contents of 'example.txt')

rename()
Description: Rename a file or directory.
Example:

rename("oldname.txt", "newname.txt");
// Output: (changes 'oldname.txt' to 'newname.txt')

realpath()
Description: Return the canonical absolute pathname.
Example:

echo realpath("example.txt");
// Output: (full path to 'example.txt')

rewind()
Description: Set the file pointer to the beginning of a file.
Example:

$file = fopen("example.txt", "r");
rewind($file);
fclose($file);
// Output: (moves file pointer to start)

stat()
Description: Retrieve detailed information about a file.
Example:

print_r(stat("example.txt"));
// Output: (array of file statistics)

symlink()
Description: Create a symbolic link pointing to a specified target.
Example:

symlink("target.txt", "symbolic_link.txt");
// Output: (creates symbolic link 'symbolic_link.txt' to 'target.txt')

tmpfile()
Description: Create a temporary file in read-write mode.
Example:

$temp = tmpfile();
fwrite($temp, "Temporary data");
fclose($temp);
// Output: (creates and closes a temporary file)

touch()
Description: Set the access and modification times for a file.
Example:

touch("example.txt");
// Output: (updates 'example.txt' timestamp)

unlink()
Description: Delete a file.
Example:

unlink("example.txt");
// Output: (removes 'example.txt')

PHP Math Functions

PHP includes a range of predefined mathematical functions that facilitate operations on integer and float types. These functions are integrated into the PHP core and require no installation.

Example: Using the decbin() function in PHP:

<?php
echo decbin(12);
?>

abs()
Description: Return the absolute (positive) value of a number.
Example:

echo abs(-10);
// Output: 10

acos()
Description: Find the arc cosine of a number, returning the result in radians.
Example:

echo acos(0.5);
// Output: 1.0471975511966

acosh()
Description: Calculate the inverse hyperbolic cosine of a number.
Example:

echo acosh(2);
// Output: 1.3169578969248

asin()
Description: Calculate the arc sine of a number in radians.
Example:

echo asin(0.5);
// Output: 0.5235987755983

asinh()
Description: Find the inverse hyperbolic sine of a number
Example:.

echo asinh(1);
// Output: 0.88137358701954

atan2()
Description: Calculate the arc tangent of two numbers x and y.
Example:

echo atan2(1, 1);
// Output: 0.78539816339745

atan()
Description: Return the arc tangent of a number, result in radians.
Example:

echo atan(1);
// Output: 0.78539816339745

atanh()
Description: Find the inverse hyperbolic tangent of a number.
Example:

$file = fopen("example.txt", "r");
echo fgets($file); // Outputs one line
fclose($file);

base_convert()
Description: Convert a number from one base to another.
Example:

echo base_convert("A1", 16, 2);
// Output: 10100001

bindec()
Description: Convert a binary string to its decimal equivalent.
Example:

echo bindec("1101");
// Output: 13

ceil()
Description: Round a number up to the nearest integer.
Example:

echo ceil(4.3);
// Output: 5

cos()
Description: Find the cosine of a number (in radians).
Example:

echo cos(1);
// Output: 0.54030230586814

cosh()
Description: Calculate the hyperbolic cosine of a number.
Example:

echo cosh(1);
// Output: 1.5430806348152

decbin()
Description: Convert a decimal number to binary.
Example:

echo decbin(12);
// Output: 1100

dechex()
Description: Convert a decimal number to hexadecimal.
Example:

echo dechex(255);
// Output: ff

decoct()
Description: Convert a decimal number to octal.
Example:

echo decoct(15);
// Output: 17

deg2rad()
Description: Convert degrees to radians.
Example:

echo deg2rad(180);
// Output: 3.1415926535898

exp()
Description: Calculate e raised to the power of a given number.
Example:

echo exp(2);
// Output: 7.3890560989306

expm1()
Description: Calculate e raised to the power of a given number minus one.
Example:

echo expm1(1);
// Output: 1.718281828459

hypot()
Description: Returns the square root of the sum of squares of two numbers.
Example:

echo hypot(3, 4);
// Output: 5

fmod()
Description: Calculate the remainder of a division (modulo operation).
Example:

echo fmod(5.7, 1.3);
// Output: 0.5

hexdec()
Description: Convert a hexadecimal string to its decimal equivalent.
Example:

echo hexdec("ff");
// Output: 255

hypot()
Description: Calculate the length of the hypotenuse of a right-angled triangle.
Example:

echo hypot(3, 4);
// Output: 5

intdiv()
Description: Calculate the integer quotient of the division of two numbers.
Example:

echo intdiv(7, 3);
// Output: 2

is_finite()
Description: Check if a number is finite.
Example:

echo is_finite(1.2e308) ? "Finite" : "Infinite";
// Output: Finite

is_infinite()
Description: Check if a number is infinite.
Example:

echo is_infinite(1.2e308 * 10) ? "Infinite" : "Finite";
// Output: Infinite

is_nan()
Description: Check if a value is ‘not a number’.
Example:

echo is_nan(acos(2)) ? "Not a number" : "Number";
// Output: Not a number

is_readable()
Description: Determine if a file exists and is readable.
Example:

echo is_readable("example.txt") ? "Readable" : "Not readable";
// Output: Readable or Not readable

is_uploaded_file()
Description: Check if a file was uploaded via HTTP POST.
Example:

echo is_uploaded_file($_FILES['file']['tmp_name']) ? "Uploaded" : "Not uploaded";
// Output: Uploaded or Not uploaded

is_writable()
Description: Verify if a file is writable.
Example:

echo is_writable("example.txt") ? "Writable" : "Not writable";
// Output: Writable or Not writable

link()
Description: Create a hard link for a specified target.
Example:

link("target.txt", "hardlink.txt");
// Output: (creates a hard link 'hardlink.txt' pointing to 'target.txt')

lstat()
Description: Retrieve information about a file or symbolic link.
Example:

print_r(lstat("example.txt"));
// Output: (array of file or symbolic link information)

mkdir()
Description: Create a new directory with the specified path.
Example:

mkdir("new_folder");
// Output: (creates 'new_folder' directory)

pathinfo()
Description: Get information about a path as an associative array or string.
Example:

print_r(pathinfo("example.txt"));
// Output: (displays path info, e.g., directory, basename, extension)

pclose()
Description: Close a pipe opened by popen().
Example:

$pipe = popen("ls", "r");
pclose($pipe);
// Output: (closes the pipe to the command 'ls')

popen()
Description: Open a pipe to a specified command.
Example:

$pipe = popen("ls", "r");
// Output: (opens a pipe to list directory contents)

readfile()
Description: Read a file and output it directly to the buffer.
Example:

readfile("example.txt");
// Output: (displays contents of 'example.txt')

realpath()
Description: Return the canonical absolute pathname.
Example:

echo realpath("example.txt");
// Output: (full path to 'example.txt')

rewind()
Description: Set the file pointer to the beginning of a file.
Example:

$file = fopen("example.txt", "r");
rewind($file);
fclose($file);
// Output: (moves file pointer to start)

stat()
Description: Retrieve detailed information about a file.
Example:

print_r(stat("example.txt"));
// Output: (array of file statistics)

symlink()
Description: Create a symbolic link pointing to a specified target.v Example:

symlink("target.txt", "symbolic_link.txt");
// Output: (creates symbolic link 'symbolic_link.txt' to 'target.txt')

tmpfile()
Description: Create a temporary file in read-write mode.
Example:

$temp = tmpfile();
fwrite($temp, "Temporary data");
fclose($temp);
// Output: (creates and closes a temporary file)

touch()
Description: Set the access and modification times for a file.
Example:

touch("example.txt");
// Output: (updates 'example.txt' timestamp)

The predefined math functions in PHP are used to handle mathematical operations with integer and float types. These math functions are built into PHP and do not require any additional installation.

Installation: These functions do not require any special installation. The complete list of PHP math functions is given below:

Example: A program illustrating the decbin() function in PHP:

<?php
echo decbin(45);
?>

Output:

101101

List of Common PHP String Functions

addcslashes()

Description: Inserts backslashes before specified characters in a string.

Example:

echo addcslashes("Hello, World!", 'o');
// Output: Hell\o, W\orld!

addslashes()

Description: Escapes special characters by adding backslashes.
Example:

echo addslashes("Hello 'World'");
// Output: Hello \'World\'

bin2hex()

Description: Converts a string to hexadecimal representation.
Example:

echo bin2hex("Hi");
// Output: 4869

chop()

Description: Removes whitespace or specified characters from the end of a string.
Example:

echo chop("Hello World!  ");
// Output: Hello World!

chr()

Description: Converts ASCII value to a character.
Example:

echo chr(65);
// Output: A

chunk_split()

Description: Splits a string into smaller chunks.
Example:

echo chunk_split("abcdef", 2, "-");
// Output: ab-cd-ef-

convert_uudecode()

Description: Decodes a uuencoded string.
Example:

$encoded = convert_uuencode("Hello");
echo convert_uudecode($encoded);
// Output: Hello

convert_uuencode()

Description: Encodes a string using the uuencode algorithm.
Example:

echo convert_uuencode("Hello");
// Output: 0=&5S=`IT

count_chars()

Description: Returns information about character frequencies in a string.
Example:

print_r(count_chars("Hello", 1));
// Output: Array ( [72] => 1 [101] => 1 [108] => 2 [111] => 1 )

crc32()

Description: Calculates the CRC32 polynomial of a string.
Example:

echo crc32("Hello");
// Output: 907060870

crypt()

Description: One-way string hashing using algorithms like DES, Blowfish, or MD5.
Example:

echo crypt("mypassword", "salt");
// Output: saGng5vH/kMmQ

password_hash()

Description: Creates a password hash using the bcrypt algorithm.
Example:

echo password_hash("mypassword", PASSWORD_DEFAULT);
// Output: $2y$10$...

echo()

Description: Outputs one or more strings.
Example:

echo "Hello", " World!";
// Output: Hello World!

explode()

Description: Splits a string by a specified delimiter into an array.
Example:

print_r(explode(" ", "Hello World"));
// Output: Array ( [0] => Hello [1] => World )

hex2bin()

Description: Converts a hexadecimal string to binary.
Example:

echo hex2bin("48656c6c6f");
// Output: Hello

implode()

Description: Joins array elements into a single string.
Example:

echo implode(", ", array("apple", "banana", "cherry"));
// Output: apple, banana, cherry

lcfirst()

Description: Converts the first character of a string to lowercase.
Example:

echo lcfirst("HELLO");
// Output: hELLO

levenshtein()

Description: Returns the Levenshtein distance between two strings.
Example:

echo levenshtein("kitten", "sitting");
// Output: 3

ltrim()

Description: Strips whitespace from the beginning of a string.
Example:

echo ltrim("    Hello");
// Output: Hello

md5_file()

Description: Generates the MD5 hash of a file.
Example:

echo md5_file("example.txt");
// Output: 5d41402abc4b2a76b9719d911017c592

md5()

Description: Generates the MD5 hash of a string.
Example:

echo md5("Hello World");
// Output: b10a8db164e0754105b7a99be72e3fe5

metaphone()

Description: Computes the metaphone key of a string for phonetic comparisons.
Example:

echo metaphone("example");
// Output: EXMPL

nl2br()

Description: Inserts HTML line breaks before newlines in a string.
Example:

echo nl2br("Hello\nWorld!");
// Output: Hello<br />World!

array_chunk()

Description:Splits an array into chunks of a specified size.

Example:

$array = array(1, 2, 3, 4, 5, 6);
print_r(array_chunk($array, 2));
// Output:
// Array
// (
//     [0] => Array ( [0] => 1 [1] => 2 )
//     [1] => Array ( [0] => 3 [1] => 4 )
//     [2] => Array ( [0] => 5 [1] => 6 )
// )

array_combine()

Description:Creates an array by combining one array as keys and another array as values.

Example:

$keys = array('fruit', 'vegetable');
$values = array('apple', 'carrot');
print_r(array_combine($keys, $values));
// Output:
// Array
// (
//     [fruit] => apple
//     [vegetable] => carrot
// )

array_count_values()

Description:Counts the occurrences of all values in an array.

Example:

$array = array(1, "hello", 1, "world", "hello");
print_r(array_count_values($array));
// Output:
// Array
// (
//     [1] => 2
//     [hello] => 2
//     [world] => 1
// )

array_diff()

Description:Computes the difference between two or more arrays.

Example:

$array1 = array("a" => "green", "b" => "brown", "c" => "blue");
$array2 = array("a" => "green", "yellow", "red");
print_r(array_diff($array1, $array2));
// Output:
// Array
// (
//     [b] => brown
//     [c] => blue
// )

array_fill()

Description:Fills an array with a specified value, starting from a specified index.

Example:

print_r(array_fill(3, 5, "apple"));
// Output:
// Array
// (
//     [3] => apple
//     [4] => apple
//     [5] => apple
//     [6] => apple
//     [7] => apple
// )

array_filter()

Description:Filters elements of an array using a callback function.

Example:

$array = array(1, 2, 3, 4, 5, 6);
print_r(array_filter($array, function($value) { return $value % 2 == 0; }));
// Output:
// Array
// (
//     [1] => 2
//     [3] => 4
//     [5] => 6
// )

array_flip()

Description:Exchanges keys and values in an array.

Example:

$array = array("a" => "apple", "b" => "banana", "c" => "cherry");
print_r(array_flip($array));
// Output:
// Array
// (
//     [apple] => a
//     [banana] => b
//     [cherry] => c
// )

array_key_exists()

Description:Checks if a specified key exists within an array.

Example:

$array = array("fruit" => "apple", "vegetable" => "carrot");
echo array_key_exists("fruit", $array) ? "Key exists" : "Key does not exist";
// Output: Key exists

array_merge()

Description:Merges one or more arrays into a single array.

Example:

$array1 = array("color" => "red", 2, 4);
$array2 = array("a", "b", "color" => "green", "shape" => "trapezoid", 4);
print_r(array_merge($array1, $array2));
// Output:
// Array
// (
//     [color] => green
//     [0] => 2
//     [1] => 4
//     [2] => a
//     [3] => b
//     [shape] => trapezoid
//     [4] => 4
// )

array_reverse()

Description:Reverses the order of elements in an array.

Example:

$array = array("a", "b", "c", "d");
print_r(array_reverse($array));
// Output:
// Array
// (
//     [0] => d
//     [1] => c
//     [2] => b
//     [3] => a
// )

array_search()

Description:Searches for a value in an array and returns the corresponding key if found.

Example:

$array = array(0 => 'blue', 1 => 'red', 2 => 'green');
echo array_search('green', $array);
// Output: 2

array_sum()

Description:Returns the sum of all values in an array.

Example:

$array = array(2, 4, 6, 8);
echo array_sum($array);
// Output: 20

array_unique()

Description:Removes duplicate values from an array.

Example:

$array = array("apple", "banana", "apple", "orange");
print_r(array_unique($array));
// Output:
// Array
// (
//     [0] => apple
//     [1] => banana
//     [3] => orange
// )

array_values()

Description:Returns all the values from an array, with numeric keys starting from 0.

Example:

$array = array("size" => "large", "color" => "red");
print_r(array_values($array));
// Output:
// Array
// (
//     [0] => large
//     [1] => red
// )

compact()

Description:Create an array using variables as keys and their values as elements.

Example:

$name = "John";
$age = 30;
print_r(compact("name", "age"));
// Output: Array ( [name] => John [age] => 30 )

count()

Description:Count the total number of elements in an array.

Example:

$array = array("apple", "banana", "cherry");
echo count($array);
// Output: 3

current()

Description:Return the value of the element at the internal pointer in an array.

Example:

$array = array("apple", "banana", "cherry");
echo current($array);
// Output: apple

end()

Description:Find the last element of a given array.

Example:

$array = array("apple", "banana", "cherry");
echo end($array);
// Output: cherry

extract()

Description:Convert array elements into variables.

Example:

$array = array("name" => "John", "age" => 30);
extract($array);
echo $name;
// Output: John

in_array()

Description:Check if a specific value exists in an array.

Example:

$array = array("apple", "banana", "cherry");
echo in_array("banana", $array) ? "Found" : "Not found";
// Output: Found

key()

Description:Return the current index or key of an array where the internal pointer points.

Example:

$array = array("a" => "apple", "b" => "banana");
echo key($array);
// Output: a

krsort()

Description:Sort an array by its keys in descending order.

Example:

$array = array("a" => "apple", "c" => "cherry", "b" => "banana");
krsort($array);
print_r($array);
// Output: Array ( [c] => cherry [b] => banana [a] => apple )

list()

Description:Assign array values to multiple variables.

Example:

$array = array("apple", "banana", "cherry");
list($fruit1, $fruit2) = $array;
echo $fruit1;
// Output: apple

natcasesort()

Description:Sort an array using natural order, case-insensitively.

Example:

$array = array("Image2.jpg", "image10.jpg", "Image1.jpg");
natcasesort($array);
print_r($array);
// Output: Array ( [0] => Image1.jpg [2] => Image2.jpg [1] => image10.jpg )

natsort()

Description:Sort an array using a “natural order” algorithm without regard to case.

Example:

$array = array("Image2.jpg", "image10.jpg", "Image1.jpg");
natsort($array);
print_r($array);
// Output: Array ( [2] => Image1.jpg [0] => Image2.jpg [1] => image10.jpg )

next()

Description:Move the internal pointer to the next element and return its value.

Example:

$array = array("apple", "banana", "cherry");
echo next($array);
// Output: banana

pos()

Description:Return the value of the current element of an array.

Example:

$array = array("apple", "banana", "cherry");
echo pos($array);
// Output: apple

prev()

Description:Move the internal pointer to the previous element and return its value.

Example:

$array = array("apple", "banana", "cherry");
next($array);
echo prev($array);
// Output: apple

range()

Description:Create an array with elements within a specified range.

Example:

print_r(range(0, 5));
// Output: Array ( [0] => 0 [1] => 1 [2] => 2 [3] => 3 [4] => 4 [5] => 5 )

reset()

Description:Move the internal pointer to the first element of an array.

Example:

$array = array("apple", "banana", "cherry");
echo reset($array);
// Output: apple

rsort()

Description:Sort an array in descending order.

Example:

$array = array(3, 1, 2);
rsort($array);
print_r($array);
// Output: Array ( [0] => 3 [1] => 2 [2] => 1 )

shuffle()

Description:Randomize the order of elements in an array.

Example:

$array = array("apple", "banana", "cherry");
shuffle($array);
print_r($array);
// Output: (random order, e.g., Array ( [0] => banana [1] => cherry [2] => apple ))

sizeof()

Description:Count the number of elements in an array or countable object.

Example:

$array = array("apple", "banana", "cherry");
echo sizeof($array);
// Output: 3

sort()

Description:Sort an array in ascending order.

Example:

$array = array(3, 1, 2);
sort($array);
print_r($array);
// Output: Array ( [0] => 1 [1] => 2 [2] => 3 )

uasort()

Description:Sort an array while maintaining index association, using a user-defined function.

Example:

$array = array("a" => 3, "b" => 1, "c" => 2);
uasort($array, function($x, $y) { return $x <=> $y; });
print_r($array);
// Output: Array ( [b] => 1 [c] => 2 [a] => 3 )

usort()

Description:Sort an array using a custom comparison function.

Example:

$array = array("apple", "banana", "cherry");
usort($array, function($x, $y) { return strlen($x) <=> strlen($y); });
print_r($array);
// Output: Array ( [0] => apple [1] => cherry [2] => banana )

PHP MySQL Database Introduction

What is MySQL?

MySQL is an open-source relational database management system (RDBMS) widely used in conjunction with PHP. It is currently one of the most popular database systems and is developed, distributed, and maintained by Oracle Corporation.

• Data within a MySQL database is organized into tables consisting of rows and columns.
• MySQL operates as a server-based database system.
• It is well-suited for both small and large-scale applications.
• Known for its speed, reliability, and ease of use, MySQL uses standard SQL (Structured Query Language).
• MySQL can run on various platforms.

Downloading MySQL Database

You can download MySQL for free from the official MySQL website.

How to Connect PHP to a MySQL Database?

In PHP version 5 and above, MySQL can be accessed using two primary methods:

• MySQLi extension.
• PDO (PHP Data Objects).

Difference Between MySQLi and PDO

• PDO supports 12 different types of databases, while MySQLi is exclusively for MySQL databases.
• Both PDO and MySQLi offer object-oriented interfaces, but MySQLi also provides a procedural interface.
• If you need to switch your project from MySQL to another database system, PDO allows this with minimal changes to the connection string and a few queries. With MySQLi, you would have to rewrite the entire codebase, including all queries.

Ways to Work with MySQL in PHP

There are three primary methods to connect and interact with a MySQL database in PHP:

1. MySQLi (Object-Oriented)
2. MySQLi (Procedural)
3. PDO (PHP Data Objects)

Connecting to a MySQL Database using PHP

Below are the three different approaches to connect to a MySQL database from a PHP script.

1. MySQLi Object-Oriented Approach: You can use the object-oriented approach with MySQLi to create a connection to the MySQL database.

Syntax:

<?php
$servername = "localhost";
$username = "username";
$password = "password";

// Create connection
$conn = new mysqli($servername, $username, $password);

// Check connection
if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
}
echo "Connected successfully";
?>

Output:

Connected successfully

2. MySQLi Procedural Approach: You can also establish a connection using MySQLi’s procedural interface.

Syntax:

<?php
$servername = "localhost";
$username = "username";
$password = "password";

// Create connection
$conn = mysqli_connect($servername, $username, $password);

// Check connection
if (!$conn) {
    die("Connection failed: " . mysqli_connect_error());
}
echo "Connected successfully";
?>

Output:

Connected successfully

3. PDO Approach: PDO offers a unified interface for connecting to a MySQL database and can be easily adapted for other database systems.

Syntax:

<?php
$servername = "localhost";
$username = "username";
$password = "password";

try {
    $conn = new PDO("mysql:host=$servername;dbname=myDB", $username, $password);
    // Set PDO error mode to exception
    $conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
    echo "Connected successfully";
}
catch(PDOException $e) {
    echo "Connection failed: " . $e->getMessage();
}
?>

Output:

Connected successfully

PHP MySQL ( Creating Database )

What is a Database?

A database is a structured collection of related data that allows efficient storage, retrieval, insertion, and deletion of information. It organizes data into tables, views, schemas, reports, etc., facilitating streamlined data management. For instance, a university database may organize data about students, faculty, and administration, which enables effective data operations such as retrieval and insertion.

To create a database in MySQL, a SQL query is needed. Here are the steps to create a MySQL database using PHP:

1. Establish a connection to the MySQL server from the PHP script.
2. If the connection is successful, write a SQL query to create a database and store it in a string variable.
3. Execute the query.

We already know how to establish a connection and create variables in PHP. The query can be executed in three different ways, as shown below:

1. Using MySQLi Object-Oriented Approach: If the MySQL connection is made using the object-oriented approach, the query() method of the mysqli class is used to run the query.

Syntax:

<?php
$servername = "localhost";
$username = "username";
$password = "password";

// Establishing connection
$conn = new mysqli($servername, $username, $password);

// Checking connection
if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
}

// SQL query to create a database named newDB
$sql = "CREATE DATABASE newDB";
if ($conn->query($sql) === TRUE) {
    echo "Database created successfully with the name newDB";
} else {
    echo "Error creating database: " . $conn->error;
}

// Closing connection
$conn->close();
?>

Output:

Database created successfully with the name newDB

2. Using MySQLi Procedural Approach: If the MySQL connection is established using the procedural approach, the mysqli_query() function is used to execute the query.

Syntax:

<?php
$servername = "localhost";
$username = "username";
$password = "password";

// Establishing connection
$conn = mysqli_connect($servername, $username, $password);

// Checking connection
if (!$conn) {
    die("Connection failed: " . mysqli_connect_error());
}

// SQL query to create a database named newDB
$sql = "CREATE DATABASE newDB";
if (mysqli_query($conn, $sql)) {
    echo "Database created successfully with the name newDB";
} else {
    echo "Error creating database: " . mysqli_error($conn);
}

// Closing connection
mysqli_close($conn);
?>

Output:

Database created successfully with the name newDB

3. Using PDO Approach: If the connection is made using PDO, the query can be executed as shown below.

Syntax:

<?php
$servername = "localhost";
$username = "username";
$password = "password";

try {
    $conn = new PDO("mysql:host=$servername;dbname=newDB", $username, $password);
    // Setting PDO error mode to exception
    $conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

    // SQL query to create a database named newDB
    $sql = "CREATE DATABASE newDB";

    // Executing the query using exec() as no results are returned
    $conn->exec($sql);
    echo "Database created successfully with the name newDB";
}
catch(PDOException $e) {
    echo $sql . "<br>" . $e->getMessage();
}

// Closing the connection
$conn = null;
?>

Output:

Database created successfully with the name newDB

PHP Database connection

The collection of related data is called a database.

XAMPP is an abbreviation for Cross-Platform, Apache, MySQL, PHP, and Perl. It is a lightweight and straightforward local server used for website development.

Requirements:

Procedure to use the XAMPP web server:

1. Start the XAMPP server by running Apache and MySQL.
2. Write a PHP script for connecting to the XAMPP server.
3. Run the script in your local browser.
4. A database is created based on the PHP code.

In PHP, we can connect to a database using the XAMPP server by navigating to the following path:

“localhost/phpmyadmin”

Steps in Detail:

1. Open XAMPP and start the Apache, MySQL, and FileZilla services.
2. Now open your PHP file and write the PHP code to create a database and a table.

PHP Code to Create a Database:

<?php

// Server name is typically localhost
$servername = "localhost";

// Username for XAMPP is generally root
$username = "root";

// No password by default in XAMPP
$password = "";

// Establishing a connection
$conn = new mysqli($servername, $username, $password);

// Checking the connection
if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
}

// SQL to create a database named myDB
$sql = "CREATE DATABASE myDB";
if ($conn->query($sql) === TRUE) {
    echo "Database 'myDB' created successfully";
} else {
    echo "Error creating database: " . $conn->error;
}

// Closing the connection
$conn->close();
?>

Steps to Follow:

• Save the file as “create_database.php” in the htdocs folder located in your XAMPP installation directory.
• Open your web browser and navigate to localhost/create_database.php.

Final Step:

• The database will be created and connected to PHP.
• To view your newly created database, type localhost/phpmyadmin in your web browser, and the database will appear.

Output:

Database 'myDB' created successfully

Connect PHP to MySQL

MySQL can run on a server and is well-suited for both small and large applications. It is known for being fast, reliable, and easy to use. Additionally, it supports SQL standards and is available on multiple platforms.

How to Connect PHP with MySQL?

Starting with PHP 5, there are two main ways to interact with MySQL databases:

• MySQLi extension (where “i” stands for “improved”)
• PDO (PHP Data Objects)

Should You Use MySQLi or PDO?

Both MySQLi and PDO have their advantages:

• PDO works with 12 different types of databases, whereas MySQLi is specifically designed to work only with MySQL databases.
• If you foresee switching to another database system, PDO simplifies the transition by only requiring changes to the connection string and some queries. With MySQLi, you would need to rewrite the entire codebase, including queries.
• Both provide object-oriented interfaces, though MySQLi also offers a procedural API.

In short, if you are only using MySQL, both are good options, but if you may switch databases, PDO is more flexible.

Connecting PHP to MySQL

Using MySQLi (Object-Oriented): Here is how you can establish a connection to a MySQL database using MySQLi in object-oriented style:

<?php
$server = "localhost";
$user = "admin";
$pass = "admin123";

// Establishing the connection
$connection = new mysqli($server, $user, $pass);

// Check the connection
if ($connection->connect_error) {
    die("Connection failed: " . $connection->connect_error);
}

echo "Connection successful!";
?>

Output:

Connection successful!

Using MySQLi (Procedural): The procedural approach to connect PHP with MySQL using MySQLi looks like this:

<?php
$server = "localhost";
$user = "admin";
$pass = "admin123";

// Establishing the connection
$connection = mysqli_connect($server, $user, $pass);

// Checking the connection
if (!$connection) {
    die("Connection failed: " . mysqli_connect_error());
}

echo "Connection successful!";
?>

Output:

Connection successful!

PHP MySQL ( Creating Table )

What is a Table?

In relational and flat file databases, a table refers to an organized structure where data elements are stored in the form of vertical columns and horizontal rows. Each row represents a data record, and each column represents a specific field. A table has a fixed number of columns but can have an unlimited number of rows. The point where a row and column meet is known as a cell.

Creating a MySQL Table Using MySQLi and PDO

The process of creating a table is similar to creating a database. However, instead of creating a new database, you will connect to an existing database and define a table within it. To connect to an existing database, you need to specify the database name during the connection to MySQL.

The CREATE TABLE statement is used to define a new table.

In the following example, we will create a table named “customers” with four columns: customer_id, first_name, last_name, and email.

The data types used are:

• VARCHAR: Holds a string of variable length, containing letters, numbers, and special characters. The maximum size is defined in parentheses.
• INT: Holds integer values, ranging between -2147483648 to 2147483647.

Attributes used:

• NOT NULL: Ensures that every row must have a value in the column.
• PRIMARY KEY: Uniquely identifies each row in the table. Often applied to an ID column.

Creating a Table Using MySQLi Object-Oriented Procedure

<?php
$server = "localhost";
$user = "root";
$pass = "";
$dbname = "shopDB";

// Establishing connection
$conn = new mysqli($server, $user, $pass, $dbname);

// Checking the connection
if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
}

// SQL code to create the table
$sql = "CREATE TABLE customers (
        customer_id INT(3) PRIMARY KEY,
        first_name VARCHAR(40) NOT NULL,
        last_name VARCHAR(40) NOT NULL,
        email VARCHAR(60)
        )";

if ($conn->query($sql) === TRUE) {
    echo "Table customers created successfully";
} else {
    echo "Error creating table: " . $conn->error;
}

// Closing connection
$conn->close();
?>

Creating a Table Using MySQLi Procedural Procedure

<?php
$server = "localhost";
$user = "root";
$pass = "";
$dbname = "shopDB";

// Establishing connection
$conn = mysqli_connect($server, $user, $pass, $dbname);

// Checking connection
if (!$conn) {
    die("Connection failed: " . mysqli_connect_error());
}

// SQL code to create the table
$sql = "CREATE TABLE customers (
        customer_id INT(3) PRIMARY KEY,
        first_name VARCHAR(40) NOT NULL,
        last_name VARCHAR(40) NOT NULL,
        email VARCHAR(60)
        )";

if (mysqli_query($conn, $sql)) {
    echo "Table customers created successfully";
} else {
    echo "Error creating table: " . mysqli_error($conn);
}

// Closing connection
mysqli_close($conn);
?>

Output:

Table customers created successfully

Creating a Table Using PDO

<?php
$server = "localhost";
$user = "root";
$pass = "";
$dbname = "shopDB";

try {
    // Establishing connection
    $conn = new PDO("mysql:host=$server;dbname=$dbname", $user, $pass);

    // Setting PDO error mode to exception
    $conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

    // SQL code to create the table
    $sql = "CREATE TABLE customers (
            customer_id INT(4) UNSIGNED AUTO_INCREMENT PRIMARY KEY,
            first_name VARCHAR(40) NOT NULL,
            last_name VARCHAR(40) NOT NULL,
            email VARCHAR(60)
            )";

    // Using exec() as no results are returned
    $conn->exec($sql);
    echo "Table customers created successfully";
}
catch(PDOException $e) {
    echo $sql . "<br>" . $e->getMessage();
}

// Closing connection
$conn = null;
?>

Output:

Table customers created successfully

PHP Inserting into MySQL database

Inserting Data into a MySQL Database Using PHP

Inserting data into a MySQL database using PHP is a key task in many web applications. This allows developers to dynamically manage and store data, such as user inputs, for a wide variety of tasks like content management, e-commerce, and more.

In this section, we’ll explore how to insert records into a MySQL database using PHP. The process involves creating a connection to the database, writing an SQL INSERT statement, executing it, and handling any potential errors.

Inserting Data Using MySQLi (Object-Oriented Approach)

Let’s assume we are inserting a new record into a MySQL table named people. The objective is to add the name, surname, and age of an individual.

<?php
$mysqli = new mysqli("localhost", "admin", "password123", "mydatabase");

// Check connection
if ($mysqli === false) {
    die("ERROR: Could not connect. " . $mysqli->connect_error);
}

// Insert data
$sql = "INSERT INTO people (name, surname, age)
        VALUES ('John', 'Doe', '30')";

if ($mysqli->query($sql) === true) {
    echo "Record inserted successfully.";
} else {
    echo "ERROR: Could not execute $sql. " . $mysqli->error;
}

// Close connection
$mysqli->close();
?>

Output:

Record inserted successfully.

Inserting Data Using MySQLi (Procedural Approach)

In this case, we are inserting data into the people table using the MySQLi procedural method. The values to be added are Anna, Smith, and 24 for name, surname, and age, respectively.

<?php
$link = mysqli_connect("localhost", "admin", "password123", "mydatabase");

// Check connection
if ($link === false) {
    die("ERROR: Could not connect. " . mysqli_connect_error());
}

// Insert data
$sql = "INSERT INTO people (name, surname, age)
        VALUES ('Anna', 'Smith', '24')";

if (mysqli_query($link, $sql)) {
    echo "Record added successfully.";
} else {
    echo "ERROR: Could not execute $sql. " . mysqli_error($link);
}

// Close connection
mysqli_close($link);
?>

Output:

Record added successfully.

Inserting Data Using PDO

In this example, we are inserting data into the people table using the PDO method. The script will handle any errors that might occur during the connection or execution phases.

<?php
try {
    $pdo = new PDO("mysql:host=localhost;dbname=mydatabase", "admin", "password123");
    $pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
} catch (PDOException $e) {
    die("ERROR: Could not connect. " . $e->getMessage());
}

try {
    // Insert data
    $sql = "INSERT INTO people (name, surname, age)
            VALUES ('David', 'Lee', '28')";
    $pdo->exec($sql);
    echo "Record inserted successfully.";
} catch (PDOException $e) {
    die("ERROR: Could not execute $sql. " . $e->getMessage());
}

// Close connection
unset($pdo);
?>

Output:

Record inserted successfully.

Inserting Multiple Rows into a Table

You can also insert multiple rows into a table with a single INSERT query. To do this, add multiple sets of values within the query, where each set is enclosed in parentheses and separated by commas.

Inserting Multiple Rows Using MySQLi (Object-Oriented Approach)

<?php
$mysqli = new mysqli("localhost", "admin", "password123", "mydatabase");

// Check connection
if ($mysqli === false) {
    die("ERROR: Could not connect. " . $mysqli->connect_error);
}

// Insert multiple rows
$sql = "INSERT INTO people (name, surname, age)
        VALUES ('Alice', 'Brown', '22'),
               ('Tom', 'Harris', '35'),
               ('Emily', 'Clark', '27'),
               ('Luke', 'Morris', '31')";

if ($mysqli->query($sql) === true) {
    echo "Records inserted successfully.";
} else {
    echo "ERROR: Could not execute $sql. " . $mysqli->error;
}

// Close connection
$mysqli->close();
?>

Output:

Records inserted successfully.

Inserting Multiple Rows Using MySQLi (Procedural Approach)

<?php
$link = mysqli_connect("localhost", "admin", "password123", "mydatabase");

// Check connection
if ($link === false) {
    die("ERROR: Could not connect. " . mysqli_connect_error());
}

// Insert multiple rows
$sql = "INSERT INTO people (name, surname, age)
        VALUES ('Michael', 'Smith', '40'),
               ('Nina', 'Johnson', '29'),
               ('Chris', 'Evans', '33'),
               ('Sophia', 'Martinez', '24')";

if (mysqli_query($link, $sql)) {
    echo "Records added successfully.";
} else {
    echo "ERROR: Could not execute $sql. " . mysqli_error($link);
}

// Close connection
mysqli_close($link);
?>

Output:

Records added successfully.

Inserting Multiple Rows Using PDO

<?php
try {
    $pdo = new PDO("mysql:host=localhost;dbname=mydatabase", "admin", "password123");
    $pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
} catch (PDOException $e) {
    die("ERROR: Could not connect. " . $e->getMessage());
}

try {
    // Insert multiple rows
    $sql = "INSERT INTO people (name, surname, age)
            VALUES ('Olivia', 'Taylor', '21'),
                   ('James', 'Wilson', '37'),
                   ('Isabella', 'Garcia', '30'),
                   ('Liam', 'White', '45')";
    $pdo->exec($sql);
    echo "Records inserted successfully.";
} catch (PDOException $e) {
    die("ERROR: Could not execute $sql. " . $e->getMessage());
}

// Close connection
unset($pdo);
?>

Output:

Records inserted successfully.

PHP MySQL Delete Query

The DELETE query is used to remove records from a table in a database. It is often used with a SELECT statement to delete only those rows that meet a certain condition.

Syntax:

The basic syntax for a DELETE query is as follows:

Example Implementation:

Let us consider a table called Employees with four columns: EmployeeID, FirstName, LastName, and Position. Below are examples of how to delete the record of an employee whose EmployeeID is 101 from the Employees table using different MySQLi and PDO methods.

1. DELETE Query Using MySQLi Procedural Method:

<?php
$link = mysqli_connect("localhost", "root", "", "CompanyDB");

if ($link === false) {
    die("ERROR: Could not connect. " . mysqli_connect_error());
}

$sql = "DELETE FROM Employees WHERE EmployeeID = 101";
if (mysqli_query($link, $sql)) {
    echo "Record deleted successfully.";
} else {
    echo "ERROR: Could not execute $sql. " . mysqli_error($link);
}

mysqli_close($link);
?>

Output:

This code will delete the record where the EmployeeID is 101 from the Employees table. After execution, a confirmation message will be displayed: “Record deleted successfully.”

2. SELECT Query Using MySQLi Object-Oriented Method:

<?php
$mysqli = new mysqli("localhost", "root", "", "SampleDB");

if ($mysqli === false) {
    die("ERROR: Could not connect. " . $mysqli->connect_error);
}

$sql = "SELECT * FROM Users";
if ($res = $mysqli->query($sql)) {
    if ($res->num_rows > 0) {
        echo "<table>";
        echo "<tr>";
        echo "<th>FirstName</th>";
        echo "<th>LastName</th>";
        echo "<th>Age</th>";
        echo "</tr>";
        while ($row = $res->fetch_array()) {
            echo "<tr>";
            echo "<td>".$row['FirstName']."</td>";
            echo "<td>".$row['LastName']."</td>";
            echo "<td>".$row['Age']."</td>";
            echo "</tr>";
        }
        echo "</table>";
        $res->free();
    } else {
        echo "No records found.";
    }
} else {
    echo "ERROR: Could not execute $sql. " . $mysqli->error;
}
$mysqli->close();
?>

Output:

Similar to the previous example, this code will output the data in an HTML table format. If there are no matching records, it will show “No records found.”

PHP MySQL WHERE Clause

The WHERE clause is used to filter records based on a specific condition provided by the user. Essentially, it helps restrict the number of rows returned or affected by a SELECT, UPDATE, or DELETE query.

Syntax:

The basic syntax for using the WHERE clause is as follows:

SELECT Column1, Column2, ...
FROM Table_Name
WHERE Condition;

Example of WHERE Clause:

Let’s consider a table called Students with three columns: FirstName, LastName, and Age.

To retrieve all the rows where the FirstName is “John”, we will use the following code examples:

1. WHERE Clause Using MySQLi Procedural Method:

<?php
$link = mysqli_connect("localhost", "root", "", "SchoolDB");

if ($link === false) {
    die("ERROR: Could not connect. " . mysqli_connect_error());
}

$sql = "SELECT * FROM Students WHERE FirstName='John'";
if ($res = mysqli_query($link, $sql)) {
    if (mysqli_num_rows($res) > 0) {
        echo "<table>";
        echo "<tr>";
        echo "<th>FirstName</th>";
        echo "<th>LastName</th>";
        echo "<th>Age</th>";
        echo "</tr>";
        while ($row = mysqli_fetch_array($res)) {
            echo "<tr>";
            echo "<td>" . $row['FirstName'] . "</td>";
            echo "<td>" . $row['LastName'] . "</td>";
            echo "<td>" . $row['Age'] . "</td>";
            echo "</tr>";
        }
        echo "</table>";
        mysqli_free_result($res);
    } else {
        echo "No matching records found.";
    }
} else {
    echo "ERROR: Could not execute $sql. " . mysqli_error($link);
}

mysqli_close($link);
?>

Output:

This code fetches all records from the Students table where the FirstName is “John.” The matching rows are displayed in a table format.

2. WHERE Clause Using MySQLi Object-Oriented Method:

<?php
$mysqli = new mysqli("localhost", "root", "", "SchoolDB");

if ($mysqli === false) {
    die("ERROR: Could not connect. " . $mysqli->connect_error);
}

$sql = "SELECT * FROM Students WHERE FirstName='John'";
if ($res = $mysqli->query($sql)) {
    if ($res->num_rows > 0) {
        echo "<table>";
        echo "<tr>";
        echo "<th>FirstName</th>";
        echo "<th>LastName</th>";
        echo "<th>Age</th>";
        echo "</tr>";
        while ($row = $res->fetch_array()) {
            echo "<tr>";
            echo "<td>" . $row['FirstName'] . "</td>";
            echo "<td>" . $row['LastName'] . "</td>";
            echo "<td>" . $row['Age'] . "</td>";
            echo "</tr>";
        }
        echo "</table>";
        $res->free();
    } else {
        echo "No matching records found.";
    }
} else {
    echo "ERROR: Could not execute $sql. " . $mysqli->error;
}

$mysqli->close();
?>

Output:

In this example, the object-oriented method retrieves all the rows from the Students table where the FirstName is “John” and displays them in a table format.

3. WHERE Clause Using PDO Method:

<?php
try {
    $pdo = new PDO("mysql:host=localhost;dbname=SchoolDB", "root", "");
    $pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
} catch (PDOException $e) {
    die("ERROR: Could not connect. " . $e->getMessage());
}

try {
    $sql = "SELECT * FROM Students WHERE FirstName='John'";
    $res = $pdo->query($sql);
    if ($res->rowCount() > 0) {
        echo "<table>";
        echo "<tr>";
        echo "<th>FirstName</th>";
        echo "<th>LastName</th>";
        echo "<th>Age</th>";
        echo "</tr>";
        while ($row = $res->fetch()) {
            echo "<tr>";
            echo "<td>" . $row['FirstName'] . "</td>";
            echo "<td>" . $row['LastName'] . "</td>";
            echo "<td>" . $row['Age'] . "</td>";
            echo "</tr>";
        }
        echo "</table>";
        unset($res);
    } else {
        echo "No matching records found.";
    }
} catch (PDOException $e) {
    die("ERROR: Could not execute $sql. " . $e->getMessage());
}

unset($pdo);
?>

Output:

The PDO example runs a query to select all rows from the Students table where the FirstName is “John.” The results are displayed in a table format.

PHP MySQL UPDATE Query

The MySQL UPDATE query is utilized to modify existing records in a table within a MySQL database.

It allows updating one or more fields simultaneously and can be used in conjunction with the WHERE clause to specify conditions for the update.

Syntax:

The basic syntax for the UPDATE query is as follows:

UPDATE table_name
SET column1 = value1, column2 = value2, ...
WHERE condition;

Example of WHERE Update Query:

Let’s consider a table called Employees with columns ID, FirstName, LastName, and Age.

To update the Age of an employee with ID 105 in the Employees table, we can use the following code:

1. Update Query Using MySQLi Procedural Method:

<?php
$link = mysqli_connect("localhost", "root", "", "CompanyDB");

if ($link === false) {
    die("ERROR: Could not connect. " . mysqli_connect_error());
}

$sql = "UPDATE Employees SET Age='32' WHERE ID=105";
if (mysqli_query($link, $sql)) {
    echo "Record was updated successfully.";
} else {
    echo "ERROR: Could not execute $sql. " . mysqli_error($link);
}

mysqli_close($link);
?>

Output:

This code updates the Age of the employee with ID 105 to 32. If successful, a message is displayed indicating the update.

2. Update Query Using MySQLi Object-Oriented Method:

<?php
$mysqli = new mysqli("localhost", "root", "", "CompanyDB");

if ($mysqli === false) {
    die("ERROR: Could not connect. " . $mysqli->connect_error);
}

$sql = "UPDATE Employees SET Age='32' WHERE ID=105";
if ($mysqli->query($sql) === true) {
    echo "Record was updated successfully.";
} else {
    echo "ERROR: Could not execute $sql. " . $mysqli->error;
}

$mysqli->close();
?>

Output:

In this example, the Age of the employee with ID 105 is updated to 32. A success message is shown if the query is executed without errors.

3. Update Query Using PDO Method:

<?php
try {
    $pdo = new PDO("mysql:host=localhost;dbname=CompanyDB", "root", "");
    $pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
} catch (PDOException $e) {
    die("ERROR: Could not connect. " . $e->getMessage());
}

try {
    $sql = "UPDATE Employees SET Age='32' WHERE ID=105";
    $pdo->exec($sql);
    echo "Record was updated successfully.";
} catch (PDOException $e) {
    die("ERROR: Could not execute $sql. " . $e->getMessage());
}

unset($pdo);
?>

Output:

This PDO method updates the Age of the employee with ID 105 to 32, and a confirmation message is displayed upon successful execution.

PHP MySQL LIMIT Clause

In MySQL, the LIMIT clause is used in conjunction with the SELECT statement to control the number of rows returned in the result set. The LIMIT clause accepts either one or two arguments: offset and count. Both values must be non-negative integers.

• Offset: This specifies the position of the first row to return.
• Count: This defines the maximum number of rows to return.

When two parameters are used, the first one represents the offset and the second indicates the count. If only one parameter is provided, it represents the number of rows to return from the start of the result set.

Syntax:

SELECT column1, column2, ...
FROM table_name
LIMIT offset, count;

Example:

Let’s consider the following table named Employees, which contains three columns: FirstName, LastName, and Age.

To retrieve the first two rows from the Employees table, use the following query:

SELECT * FROM Employees LIMIT 2;

To fetch rows starting from the second row and retrieve two rows (rows 2 and 3 inclusive), use the following query:

SELECT * FROM Employees LIMIT 1, 2;

Below is the PHP implementation of the query to display the first two rows from the Employees table using the LIMIT clause in both procedural and object-oriented methods:

1. Limit Clause Using MySQLi Procedural Method:

<?php
$link = mysqli_connect("localhost", "root", "", "CompanyDB");

if ($link === false) {
    die("ERROR: Could not connect. " . mysqli_connect_error());
}

$sql = "SELECT * FROM Employees LIMIT 2";
if ($res = mysqli_query($link, $sql)) {
    if (mysqli_num_rows($res) > 0) {
        echo "<table>";
        echo "<tr>";
        echo "<th>FirstName</th>";
        echo "<th>LastName</th>";
        echo "<th>Age</th>";
        echo "</tr>";
        while ($row = mysqli_fetch_array($res)) {
            echo "<tr>";
            echo "<td>" . $row['FirstName'] . "</td>";
            echo "<td>" . $row['LastName'] . "</td>";
            echo "<td>" . $row['Age'] . "</td>";
            echo "</tr>";
        }
        echo "</table>";
        mysqli_free_result($res);
    } else {
        echo "No matching records were found.";
    }
} else {
    echo "ERROR: Could not execute $sql. " . mysqli_error($link);
}

mysqli_close($link);
?>

Output:

This code retrieves and displays the first two rows from the Employees table, showing FirstName, LastName, and Age fields.

PHP Classes

Like C++ and Java, PHP supports object-oriented programming (OOP). Classes in PHP are the blueprints for creating objects. One key difference between functions and classes is that a class can contain both data (properties/variables) and functions (methods) that define the behavior of an object.

A class is essentially a programmer-defined data type that includes local methods and properties. It serves as a collection of objects, each having specific attributes and behavior.

Syntax:

To define a class, start with the keyword class followed by the name of the class.

<?php
    class ExampleClass {

    }
?>

Note: Classes are enclosed using curly braces {}, similar to how functions are defined.

Below are examples illustrating the use of classes in PHP’s object-oriented programming:

Example 1: Constructor in PHP Class

A constructor is a special method that gets called automatically when an object of the class is created. In PHP, constructors are defined using __construct().

<?php
class MyClass
{
    // Constructor
    public function __construct(){
        echo 'The class "' . __CLASS__ . '" has been instantiated!<br>';
    }

}

// Create a new object of the class
$obj = new MyClass;
?>

Output:

The class "MyClass" has been instantiated!

Example 2: Destructor in PHP Class

A destructor is another special method that is invoked automatically when an object is no longer in use or the script execution ends. In PHP, destructors are defined using __destruct().

<?php
class MyClass
{
    // Destructor
    public function __destruct(){
        echo 'The class "' . __CLASS__ . '" has been destroyed!';
    }

}

// Create a new object of the class
$obj = new MyClass;
?>

Output:

The class "MyClass" has been destroyed!

PHP Variables

Constructors are special methods used for initial settings when new instances of a class are created. They play a key role in PHP’s object-oriented programming model introduced in PHP5. Constructors act as the blueprint for creating objects, initializing their properties, and defining their behavior. Once the object is initialized, the constructor is automatically called. In contrast, destructors handle object cleanup and are automatically invoked at the end of the script execution.

In this article, we’ll explore constructors and destructors, two important concepts in PHP’s object-oriented programming.

Both constructors and destructors are special member functions, with the primary difference being that destructors are preceded by a ~ (tilde) symbol.

Constructor Syntax:

__construct():

function __construct()
{
   // Initialize the object and its properties
}

Destructor Syntax:

__destruct():

function __destruct()
{
   // Cleanup code
}

Note: The constructor is defined in the public section of the class. It is responsible for setting the initial values of the class properties.

Types of Constructors:

1. Default Constructor: It has no parameters but can accept dynamic values during object creation.
2. Parameterized Constructor: This constructor accepts parameters and assigns them to class properties.
3. Copy Constructor: This accepts another object as an argument and initializes the new object from it.

Inheritance and Constructors:

Constructors are inherited by child classes. If a child class defines its own constructor, it will be called instead of the parent’s constructor.

Pre-defined vs. User-defined Constructor:

When a class contains both the pre-defined __construct() and a user-defined constructor, __construct() will act as the constructor while the user-defined one behaves like a regular method.

Example 1: Pre-defined Constructor in PHP Class

<?php
class Plant
{
    function Plant()
    {
        echo "This is a user-defined constructor for the Plant class.";
    }

    function __construct()
    {
        echo "This is the pre-defined constructor for the Plant class.";
    }
}

$obj = new Plant();
?>

Output:

This is the pre-defined constructor for the Plant class.

Example 2: Parameterized Constructor

In this example, the constructor takes parameters and sets the object’s properties accordingly.

<?php

class Vehicle
{
    public $make;
    public $model;

    function __construct($make, $model)
    {
        $this->make = $make;
        $this->model = $model;
    }

    function show_details()
    {
        echo "Make: " . $this->make . ", Model: " . $this->model . "\n";
    }
}

$vehicle1 = new Vehicle("Toyota", "Corolla");
$vehicle1->show_details();

$vehicle2 = new Vehicle("Honda", "Civic");
$vehicle2->show_details();

?>

Output:

Make: Toyota, Model: Corolla
Make: Honda, Model: Civic

Inheritance and Constructors

If a child class has its own constructor, both the child’s and parent’s constructors will be called in order.

Example 3: Constructor in Parent and Child Classes

<?php
class Animal
{
    function __construct()
    {
        print "Animal class constructor.\n";
    }
}

class Dog extends Animal
{
    function __construct()
    {
        parent::__construct(); // Call the parent constructor
        print "Dog class constructor.\n";
    }
}

$obj1 = new Animal();
$obj2 = new Dog();
?>

Output:

Animal class constructor.
Animal class constructor.
Dog class constructor.

Destructor in PHP

Destructors are used to clean up resources when an object is no longer needed. They are automatically called when the object goes out of scope or the script ends.

Example 4: Destructor

<?php
class Item
{
    function __construct()
    {
        echo "In constructor, ";
        $this->name = "Item Object";
    }

    function __destruct()
    {
        echo "destroying " . $this->name . "\n";
    }
}

$obj = new Item();
?>

Output:

In constructor, destroying Item Object

Note: In cases of inheritance, if both the parent and child class have destructors, the destructor of the child class is executed first, followed by the parent’s destructor.

Advantages of Constructors:

1. Automatic Initialization: Constructors allow automatic initialization of object properties when creating an instance.
2. Flexibility with Parameters: They can take multiple parameters, enabling dynamic initialization.
3. Reusability: Objects can be reused without having to reinitialize their properties each time.
4. Session Management: Constructors can initiate sessions, removing the need to start them manually in every function.

Destructor:

Destructors clean up resources and free memory before an object is destroyed. They are especially useful for closing file handles or database connections.

Constructor vs. Destructor Comparison

Constructors	Destructors
Accepts one or more parameters.	Takes no parameters.
Named as __construct().	Named as __destruct().
Called automatically when an object is created.	Called automatically when an object is destroyed.
Used for initializing an object’s properties.	Used for cleaning up resources.
Can be overloaded.	Cannot be overloaded.
Allocates memory.	Deallocates memory.

Example 5: Destructor in Inherited Class

<?php
class ParentClass
{
    function __destruct()
    {
        echo "Destructor of Parent Class\n";
    }
}

class ChildClass extends ParentClass
{
    function __destruct()
    {
        echo "Destructor of Child Class\n";
        parent::__destruct(); // Call parent destructor
    }
}

$obj = new ChildClass();
?>

Output:

Destructor of Child Class
Destructor of Parent Class

PHP Access Specifiers

In PHP, each property of a class must have one of three visibility levels, known as public, private, and protected.

• Public: Public properties can be accessed by any code, whether that code is inside or outside the class. If a property is declared public, its value can be read or changed from anywhere in your script.
• Private: Private properties of a class can be accessed only by code inside the class. If a property is declared private, only methods and objects inside the same class can access its contents.
• Protected: Protected class properties are like private properties in that they can’t be accessed by code outside the class. However, classes that inherit from the parent class can access protected properties.

Generally, it’s recommended to avoid creating public properties wherever possible. Instead, it’s safer to create private properties and methods to control how external code interacts with class properties.

Note: Attempting to access a private or protected property outside the class results in a fatal error.

PHP Access Specifier Feasibility:

Access Specifier	Access from Class	Access from Subclass	Access from Outside
Private	Yes	No	No
Protected	Yes	Yes	No
Public	Yes	Yes	Yes

Example 1: Public Access Specifier

<?php
class Calculator
{
    public $x = 100;  // public attributes
    public $y = 50;

    function add()
    {
        echo $this->x + $this->y;
        echo " ";
    }
}

class AdvancedCalculator extends Calculator
{
    function subtract()
    {
        echo $this->x - $this->y;
    }
}

$obj = new AdvancedCalculator();

// Accessing public properties and methods
$obj->add();
$obj->subtract();
?>

Output:

150 50

Example 2: Private Access Specifier

<?php
class Calculator
{
    private $a = 75;  // private attributes
    private $b = 5;

    private function divide()  // private member function
    {
        echo $this->a / $this->b;
        echo " ";
    }
}

class AdvancedCalculator extends Calculator
{
    function multiply()
    {
        echo $this->a * $this->b;  // Trying to access private properties
    }
}

$obj = new AdvancedCalculator();

// Attempting to access private method and properties
$obj->divide();  // This will cause a fatal error
$obj->multiply();  // This will cause a fatal error
?>

Output:

PHP Fatal error:  Uncaught Error: Call to private method Calculator::divide() from context

Example 3: Protected Access Specifier

<?php
class Calculator
{
    protected $x = 1000;  // protected attributes
    protected $y = 100;

    function divide()
    {
        echo $this->x / $this->y;
        echo " ";
    }
}

class AdvancedCalculator extends Calculator
{
    function subtract()
    {
        echo $this->x - $this->y;
    }
}

class OutsideClass
{
    function multiply()
    {
        echo $this->x * $this->y;  // Trying to access protected properties
    }
}

$obj = new AdvancedCalculator();

// Accessing protected method from within the subclass
$obj->divide();
$obj->subtract();

// Trying to access protected properties from an external class
$obj2 = new OutsideClass();
$obj2->multiply();  // This will cause a fatal error
?>

Output:

10
900
Fatal error:  Uncaught Error: Call to undefined method OutsideClass::multiply()

Multiple Inheritance in PHP

Multiple Inheritance refers to a feature in object-oriented programming languages where a child class can inherit properties and methods from multiple parent classes. PHP, by default, does not support multiple inheritance, but this can be achieved using Traits or Interfaces.

Using Traits for Multiple Inheritance

Traits allow you to reuse sets of methods across multiple classes. This makes it possible to mimic multiple inheritance in PHP.

Example 1: Using a Class and a Trait

<?php
// Class ExampleOne
class ExampleOne {
    public function greet() {
        echo "Hi";
    }
}

// Trait ExampleTrait
trait ExampleTrait {
    public function greetTrait() {
        echo " World";
    }
}

class Combined extends ExampleOne {
    use ExampleTrait;
    public function finalGreeting() {
        echo "\nWelcome to the PHP World!";
    }
}

$test = new Combined();
$test->greet();
$test->greetTrait();
$test->finalGreeting();
?>

Output:

Hi World
Welcome to the PHP World!

In this example, we use a class (ExampleOne) and a trait (ExampleTrait) in combination. The class Combined inherits the method from both the parent class and the trait.

Example 2: Using Multiple Traits

You can include multiple traits in a class using the use keyword.

<?php
// Trait ExampleOne
trait ExampleOne {
    public function greet() {
        echo "Hello";
    }
}

// Trait ExampleTwo
trait ExampleTwo {
    public function greetTwo() {
        echo " World";
    }
}

class MultipleTraits {
    use ExampleOne, ExampleTwo;
    public function finalMessage() {
        echo "\nPHP Multiple Traits Example";
    }
}

$test = new MultipleTraits();
$test->greet();
$test->greetTwo();
$test->finalMessage();
?>

Output:

Hello World
PHP Multiple Traits Example

In this case, two traits (ExampleOne and ExampleTwo) are used together inside the MultipleTraits class, allowing us to call methods from both traits.

Using Interfaces for Multiple Inheritance

PHP interfaces allow you to define methods that a class must implement, which enables multiple inheritance by implementing multiple interfaces.

Example 3: Using a Class and an Interface

<?php

class FirstClass {
    public function insideFirst() {
        echo "This is Class A";
    }
}

interface SecondInterface {
    public function insideSecond();
}

class InheritanceExample extends FirstClass implements SecondInterface {

    public function insideSecond() {
        echo "\nThis is Interface B";
    }

    public function inChildClass() {
        echo "\nThis is the child class";
    }
}

$example = new InheritanceExample();
$example->insideFirst();
$example->insideSecond();
$example->inChildClass();
?>

Output:

This is Class A
This is Interface B
This is the child class

PHP Constants

Constants in PHP are identifiers or names assigned to fixed values that remain unchanged throughout the program execution. Once a constant is set, it cannot be redefined or removed.

By convention, constant names are written in uppercase. By default, constants are case-sensitive and must start with a letter or an underscore, followed by letters, numbers, or underscores. Special characters, except for the underscore, are not allowed.

1. Creating a Constant Using define() Function: The define() function is commonly used to create constants in PHP.

Syntax:

define('CONSTANT_NAME', value, case_insensitive);

• name: The name of the constant.
• value: The value assigned to the constant.
• case_insensitive: Defines whether the constant should be case-insensitive. The default value is false, meaning the constant is case-sensitive.

Example: Creating Constants Using define() Function

<?php

// Creates a case-sensitive constant
define("GREETING", "Hello World");
echo GREETING . "\n";

// Creates a case-insensitive constant
define("WELCOME", "Hello Universe", true);
echo welcome;

?>

Output:

Hello World
Hello Universe

2. Creating a Constant Using const Keyword: The const keyword is another way to define constants, usually used within classes or functions. Unlike define(), constants defined using const are always case-sensitive.

Syntax:

const CONSTANT_NAME = value;

Example: Creating Constants Using const Keyword

<?php
const WEBSITE = 'MyWebsite';
echo WEBSITE;
?>

Output:

MyWebsite

3. Constants are Global: Constant global, meaning they can be accessed from any part of the script, including functions.

Example: Global Scope of Constants

<?php

define("MESSAGE", "PHP is Fun!");

function displayMessage() {
    echo MESSAGE;
}

echo MESSAGE . "\n";
displayMessage();

?>

Output:

PHP is Fun!
PHP is Fun!

In the example above, the constant MESSAGE can be accessed both inside and outside the function displayMessage() because constants have a global scope.

Difference Between Constants and Variables

Here are some key differences between constants and variables:

Feature	Constants	Variables
Syntax	Does not use $	Starts with $
Value	Immutable (cannot be changed)	Mutable (can be changed)
Case Sensitivity	Case-sensitive by default	Case-sensitive
Global Scope	Always global	Scope depends on where it’s defined (local or global)
Declaration Method	define() or const	Declared using $ symbol

This updated content keeps the same meaning and structure but has revised wording and updated examples. The examples now reflect the typical usage of constants in PHP, and their respective outputs have been adjusted accordingly.

Abstract Classes

Abstract Classes in PHP are classes where at least one method is declared as abstract. In PHP, abstract classes are defined using the abstract keyword. The main purpose of abstract classes is that any class extending the abstract class must implement the abstract methods defined in the parent class. An abstract class can also contain non-abstract methods.

Syntax Example of an Abstract Class in PHP

<?php

// Abstract class example in PHP
abstract class BaseClass
{
    // Abstract method (must be implemented by child classes)
    abstract function showData();

    // Non-abstract method
    function display()
    {
        echo "Base class method";
    }
}
?>

Key Points About Abstract Classes in PHP:

1. Cannot Instantiate Abstract Classes: Like in Java, you cannot create an instance of an abstract class in PHP.

Example:

<?php

// Abstract class
abstract class ParentClass {
    // Abstract method
    abstract function showData();
}

// Derived class extending the abstract class
class ChildClass extends ParentClass {
    function showData() {
        echo "Child class method";
    }
}

// Trying to create an instance of abstract class will cause an error
// $obj = new ParentClass();  // This will result in an error

$obj1 = new ChildClass;
$obj1->showData();

?>

Output:

Child class method

2. Abstract Classes Can Have Constructors: Similar to C++ or Java, abstract classes in PHP can contain constructors as well.

Example:

<?php

// Abstract class
abstract class ParentClass {
    function __construct() {
        echo "Abstract class constructor";
    }

    // Abstract method
    abstract function showData();
}

// Child class that extends the abstract class
class ChildClass extends ParentClass {
    function __construct() {
        echo "\nChild class constructor";
    }
    function showData() {
        echo "\nChild class showData method";
    }
}

$obj = new ChildClass;
$obj->showData();

?>

Output:

Child class constructor
Child class showData method

3. Abstract Classes Must Contain At Least One Abstract Method: In PHP, unlike Java, you cannot create an abstract class without having at least one abstract method. If you try to define an abstract method with a body, PHP will generate a runtime error.

Example:

<?php

// Invalid abstract class in PHP
abstract class ParentClass {
    // This will cause an error because an abstract method cannot have a body
    abstract function showData() {
        echo "This will cause an error";
    }
}

?>

Runtime Error:

PHP Fatal error:  Abstract function ParentClass::showData() cannot contain body

PHP Interface

Interface in PHP allows developers to define the structure of the methods that a class must implement without specifying the exact implementation. It serves as a way to enforce a contract for classes and provides a higher level of abstraction. Interfaces are similar to abstract classes but do not include any method bodies or data members. They ensure that any class implementing the interface must include the methods described.

Defining an Interface

To define an interface, we use the interface keyword, similar to how we define a class, but without providing method implementations.

Syntax Example:

<?php

interface ExampleInterface {
   public function methodOne();
   public function methodTwo();
}

?>

Key Features of Interfaces:

1. Abstract Methods: All methods in an interface are abstract, meaning they contain no method bodies.
2. Visibility Scope: Methods defined in interfaces must be public.
3. Multiple Implementations: A class can implement multiple interfaces, unlike inheritance where a class can only extend one parent class.

Implementing an Interface

To implement an interface in a class, use the implements keyword. The class that implements the interface must provide implementations for all methods defined in the interface.

Example:

<?php

interface SimpleInterface {
   public function methodOne();
   public function methodTwo();
}

class MyClass implements SimpleInterface {
   public function methodOne() {
     echo "Method One executed.\n";
   }
   public function methodTwo() {
     echo "Method Two executed.\n";
   }
}

$obj = new MyClass;
$obj->methodOne();
$obj->methodTwo();

?>

Output:

Method One executed.
Method Two executed.

Concrete Class:

A class that implements an interface is called a Concrete Class. It must provide implementations for all the methods defined by the interface. If two interfaces have the same method name, ambiguity may occur and cannot be implemented in the same class. An interface can extend another interface using the extends keyword, just like class inheritance.

Interface Inheritance Example:

<?php

interface FirstInterface {
    public function functionOne();
}

interface SecondInterface extends FirstInterface {
    public function functionTwo();
}

class MyClass implements SecondInterface {
    public function functionOne() {
        echo "Function One from First Interface\n";
    }
    public function functionTwo() {
        echo "Function Two from Second Interface\n";
    }
}

$obj = new MyClass;
$obj->functionOne();
$obj->functionTwo();

?>

Output:

Function One from First Interface
Function Two from Second Interface

Practical Example of Interface Implementation:

<?php

interface BasicInterface {
    public function showMethod1();
    public function showMethod2();
}

class DemoClass implements BasicInterface {
    public function showMethod1() {
        echo "showMethod1 called.\n";
    }
    public function showMethod2() {
        echo "showMethod2 called.\n";
    }
}

$instance = new DemoClass;
$instance->showMethod1();
$instance->showMethod2();

?>

Output:

showMethod1 called.
showMethod2 called.

Benefits of Using PHP Interfaces

• Unrelated Classes Can Share Methods:
  Interfaces allow unrelated classes to implement the same set of methods, regardless of their inheritance hierarchy.
• Supports Multiple Inheritance:
  A class can implement multiple interfaces, enabling a form of multiple inheritance, unlike classes that can only extend a single parent class.
• Focus on Interface, Not Implementation:
  Interfaces allow the developer to focus on the interaction with an object rather than worrying about the actual implementation, maintaining consistency for the user of the interface.

Static Function in PHP

In certain scenarios, it is useful to access class methods and properties directly without the need to create an instance of the class. This can be achieved using the static keyword. A method declared as static can be accessed without instantiating an object. Static methods are tied to the class itself, not a particular object instance. However, they can only interact with static properties and methods of the class.

To declare a static method, use the static keyword as shown below:

public static function exampleMethod()
{
    // Method logic here
}

Static methods can be invoked outside the class using the scope resolution operator :: as follows:

MyClass::exampleMethod();

Example: Using a Static Method as a Counter

<?php
/* Demonstrating the use of a static function as a counter */

class Counter {

    static $count;

    public static function incrementCount() {
        return self::$count++;
    }
}

Counter::$count = 1;

for($i = 0; $i < 5; ++$i) {
    echo 'The next count is: ' . Counter::incrementCount() . "\n";
}

?>

Output:

The next count is: 1
The next count is: 2
The next count is: 3
The next count is: 4
The next count is: 5

When to Use Static Methods?

The static keyword is used in cases where variables and methods are common to all instances of a class. Any logic that needs to be shared across multiple instances should be placed in static methods. Static methods in PHP are often found in utility classes that contain shared functionality, such as those in frameworks like Laravel or CakePHP.

Below is an example demonstrating the use of static methods.

Example: Static Method in PHP

<?php
/* Demonstrating static methods in PHP */

class NonStaticClass {

    public function display($message = "Hello World") {
        $this->message = $message;
        return $this->message;
    }
}

class StaticClass {
    public static function display($message) {
        $message = "This is a static method";
        return $message;
    }
}

// Create an instance of NonStaticClass
$object = new NonStaticClass();

echo $object->display('This is a non-static method');
echo "\n";
echo StaticClass::display('This is non-static');

?>

Output:

This is a non-static method
This is a static method

PHP Namespace

Similar to C++, PHP namespaces provide a way to organize code and prevent name conflicts when reusing the same class, function, or constant names. Namespaces offer an abstract structure that lets you reuse names without encountering fatal errors due to naming conflicts.

Key points about namespaces in PHP:

• They serve as containers for your PHP code, allowing code reuse and preventing conflicts.
• Namespaces can include classes (including abstracts and traits), interfaces, functions, and constants.
• The namespace keyword is used to define a namespace.
• It must be declared at the top of a file before any other code (except the declare keyword).
• A namespace can hold valid PHP code, just like a regular PHP script.

Example: Declaring a Namespace

<?php
namespace MyNamespace {

    // This is regular PHP code
    function hello()
    {
        echo 'Hello, I am running from a namespace!';
    }
}
?>

Global Namespace Declaration

If the namespace is to be declared globally (i.e., without a specific name), it is done like this:

<?php
namespace {
    // Code in the global space
}
?>

Declaring Multiple Namespaces in a Single File

You can declare multiple namespaces within a single PHP file:

<?php
namespace MyNamespace1 {
    // Code for the first namespace
}

namespace MyNamespace2 {
    // Code for the second namespace
}

namespace {
    // Code in the global namespace
}
?>

Namespaces are used to avoid conflicts and add flexibility and structure to your codebase. Just like directories in file systems, namespaces can be hierarchical. In PHP, the backslash (\) serves as the namespace separator.

Example: Using a Namespace

<?php
namespace MyNamespace;

function hello()
{
    echo 'Hello, I am running from a namespace!';
}

// This calls the function within the MyNamespace namespace
hello();

// Explicitly resolves to MyNamespace\hello
namespace\hello();
?>

Output:

Hello, I am running from a namespace!
Hello, I am running from a namespace!

Aliasing in Namespaces

Namespaces allow the use of aliases for ease of reference. The use keyword imports namespaces, and you can use the as keyword to create a custom alias.

Example: Aliasing in Namespaces

<?php
namespace MyNamespace;

require 'project/database/connection.php';

// Creating an alias for Project\Database\Connection
use Project\Database\Connection as Conn;

$connection = new Conn();

// Importing the Project\Database namespace with alias
use Project\Database as DB;

$connection = new DB\Connection();
?>

Dynamic Namespaces

Although you can dynamically include files in PHP, dynamic namespace importing is not supported.

Example: Dynamic Namespace Usage

<?php
namespace OtherProject;

$title = 'geeks';

// This is valid PHP code
require 'project/blog/title/' . $title . '.php';

// This will cause an error (invalid dynamic namespace)
use Project\Blog\title\$title;
?>

Runtime Error:

PHP Fatal error: Invalid namespace usage