PHP : Functions

In PHP, functions are blocks of code that can be defined and then called later to perform specific tasks. Functions help in organizing code, making it more modular, reusable, and easier to maintain. Here's how you define and use functions in PHP:

Defining Functions:


function functionName($parameter1, $parameter2, ...) {
    // code to be executed
}
 

  • function keyword is used to define a function.
  • functionName is the name of the function.
  • $parameter1, $parameter2, etc., are optional parameters that the function can accept.
  • Within the function body, you write the code to be executed when the function is called.

Example:


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

Calling Functions:

Once a function is defined, you can call it by its name with any required arguments.


functionName($argument1, $argument2, ...);
 

Example:


greet("John");
 

This would output: `Hello, John!`

Returning Values:

Functions can also return values using the return statement.


function add($a, $b) {
    return $a + $b;
}
 

Example:


$result = add(3, 4);
echo $result; // Output: 7
 

Optional Parameters and Default Values:

You can define default values for parameters, making them optional.


function greet($name = "World") {
    echo "Hello, $name!";
}
 

Example:


greet(); // Output: Hello, World!
greet("Alice"); // Output: Hello, Alice!
 

Variable Scope:

Variables defined inside a function are typically local to that function unless declared as global or passed as references.


$x = 5;

function myFunction() {
    global $x;
    echo $x; // Output: 5
}

myFunction();
 

Anonymous Functions (Closures):

Anonymous functions, also known as closures, can be declared without a name and assigned to a variable.


$add = function($a, $b) {
    return $a + $b;
};

echo $add(2, 3); // Output: 5
 

These are some basic concepts of PHP functions. They play a crucial role in PHP programming, enabling you to write reusable and modular code.