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Functions in PHP

A function in PHP is a block of code that performs a specific task.

  • Functions are used to organize and reuse code.
  • They can be called multiple times in a program, which helps in avoiding redundancy and improving code maintainability.
  • It can take input as argument and return value. There are thousands of built-in functions in PHP.

A function is defined using the function keyword, followed by the name of the function, parentheses (which can contain parameters), and curly braces {} to define the block of code that the function will execute.

Syntax:

function functionName() {
    // Code to be executed
}

Example:

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

Arguments (also called parameters) are values passed into functions when they are called. These arguments are used within the function to perform tasks.

Functions can accept multiple arguments and can be either by value or by reference.

  • Passing by Value: The function gets a copy of the argument’s value.
  • Passing by Reference: The function gets a reference to the original variable, meaning changes to the argument inside the function will affect the original variable.

Syntax (Passing by Value):

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

Example (Passing Arguments):

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

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

A function can return a value using the return keyword. The return statement ends the function execution and sends the result back to the calling code.

Syntax:

function functionName() {
    return value;
}

Example:

function multiply($a, $b) {
    return $a * $b;
}

$result = multiply(4, 5);
echo $result;  // Output: 20

Key Points:

  • Functions help in reusing code.
  • They can take arguments (parameters) and return values.
  • Arguments can be passed either by value or by reference.
  • Functions can return a value using the return keyword, or can simply perform an action without returning anything (void functions).

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