Introduction to PHP

PHP is a popular general-purpose scripting language especially suited to web development. It is fast, flexible, and pragmatic, powering everything from blogs to the most popular websites in the world.

Key Features

• Server-side scripting
• Easy database integration
• Open source and free
• Cross-platform compatibility
• Large community support

Installation

Install PHP from php.net or use a package manager:

sudo apt install php

Data Types

• String
• Integer
• Float
• Boolean
• Array
• Object
• NULL

Operators

• Arithmetic: +, -, *, /, %
• Assignment: =, +=, -=, etc.
• Comparison: ==, !=, <, >, <=, >=
• Logical: and, or, &&, ||, !

Conditional Statements

if ($a > $b) {
    echo "a is greater than b";
} elseif ($a == $b) {
    echo "a is equal to b";
} else {
    echo "a is less than b";
}

Loops

for ($i = 0; $i < 5; $i++) {
    echo $i;
}

while ($a < 10) {
    $a++;
}

Functions

function greet($name) {
    return "Hello, $name!";
}

Arrays

$arr = array(1, 2, 3);
echo $arr[0];

Form Handling

$name = $_POST['name'];
echo $name;

File Handling

$file = fopen("test.txt", "r");
while(!feof($file)) {
    echo fgets($file);
}
fclose($file);

Other Features

• Sessions and cookies
• Object-oriented programming
• Exception handling