PHP, which stands for "Hypertext Preprocessor," is an open-source server-side scripting language designed primarily for web development but also used as a general-purpose programming language. It is widely known for its ease of use and flexibility in creating dynamic web pages, effectively interacting with databases, and handling forms. PHP can be embedded into HTML and is especially suited for web servers. As of 2023, PHP powers a significant percentage of websites globally, including major platforms like WordPress, Facebook, and Wikipedia.
PHP was originally created by Danish-Canadian programmer Rasmus Lerdorf in 1993. It began as a set of Common Gateway Interface (CGI) binaries, which Lerdorf used to maintain his personal homepage. As interest in his initial project grew, Lerdorf expanded it into PHP/FI (Personal Home Page/Forms Interpreter) by 1995, which allowed users to collect form data and more easily manage content.
Following the release of PHP/FI, the language saw contributions from a wider community, leading to the release of PHP 3 in 1998, developed by Andi Gutmans and Zeev Suraski. This version introduced a more robust engine and features, laying the foundation for PHP 4 in 2000. PHP 5 followed in 2004, introducing object-oriented programming (OOP) capabilities and the PHP Data Objects (PDO) extension for database interaction.
Since then, PHP has seen continuous development, with PHP 7 being released in late 2015, focusing on performance improvements and new language features. As of 2021, PHP 8 was released, introducing JIT (Just In Time) compilation, union types, named arguments, and attributes, further cementing its relevance in modern web development. PHP continues to be a significant player in the landscape of programming languages, with a vast ecosystem of frameworks, libraries, and community resources.
In PHP, variables are declared with a dollar sign ($) preceding the variable name.
$greeting = "Hello, World!";
PHP supports both indexed and associative arrays, which can hold multiple values.
$fruits = array("apple", "banana", "orange");
$associativeArray = array("name" => "John", "age" => 30);
Functions in PHP can be defined using the function keyword, allowing for code reuse.
function add($a, $b) {
return $a + $b;
}
PHP has typical control structures like if, else, and switch for conditional logic.
if ($age >= 18) {
echo "Adult";
} else {
echo "Minor";
}
PHP supports various loops, including for, while, and foreach.
foreach ($fruits as $fruit) {
echo $fruit;
}
PHP supports OOP concepts, including classes and objects.
class Car {
public $color;
function __construct($color) {
$this->color = $color;
}
}
$myCar = new Car("blue");
PHP provides error handling using exceptions with try, catch, and finally.
try {
throw new Exception("An error occurred");
} catch (Exception $e) {
echo $e->getMessage();
}
PHP allows including files for modular programming.
include 'header.php';
PHP provides several built-in variables called superglobals, accessible from any scope.
echo $_POST['username'];
From PHP 7 onwards, type declarations can be used to enforce type safety.
function sum(int $a, int $b): int {
return $a + $b;
}
Common Integrated Development Environments (IDEs) for PHP include PhpStorm, Visual Studio Code, NetBeans, and Eclipse PDT. Each provides robust tools for debugging, code completion, and project management.
PHP is primarily interpreted, relying on the Zend Engine for processing PHP scripts. It can be executed in a server environment with software stacks like XAMPP or LAMP.
Typically, PHP projects are structured in directories containing source files, configuration files, and dependencies. Composer is the dependency manager commonly used for PHP applications, simplifying package management and autoloading.
PHP is primarily used for server-side scripting, but its applications extend to:
When compared to languages like JavaScript, Python, and Ruby, PHP remains a popular choice for web back-end development due to its extensive libraries and frameworks. However, while PHP is explicitly tailored for web applications, languages like Python and Ruby are often used for more general programming tasks.
Source-to-source translation, or transpilation, involves converting code from one programming language to another. Several tools exist for PHP: