PHP Functions

Function is a set of statements that perform a specific task which enclosed by {}. 

There are 3 components of function. They are:

• Function Prototype/Declaration
• Function Definition
• Function Call

Syntax:-

return_type function_name (parameter or argument list)
{
	function body;
}

Syntax

return_type function_name([argument type]);

It does not require name of arguments to be provided, type of arguments can be specified.

Function Definition:

It consists body of the function. The body consists of a block of statements to be performed. When a function is called, the responsibility is transferred to the function definition.

return_type function_name([arguments])
{
	statement(s);
}

Function Call:

Syntax

function_name([actual arguments]);

Advantages Of Function:

• Avoid repetition of codes.
• Code re-usability.
• Increases program readability.
• Develop an application in modules.
• Divide a complex problem into simple.
• Debugging in the program is easy.
• Modifying the program becomes easy.
• In function no need to write a lot of code.
• Reduces chances of error.

Example:-

<?php
// Function declaration and definition
function sum($num1, $num2) {
    $sum = $num1 + $num2;
    return $sum;
}

// Main logic
$a = 100;
$b = 12;
$result = sum($a, $b); // Calling the function

echo "Sum of two numbers value is : " . $result . "\n";
?>

Types Of Functions:

There are two types of functions. They are

• Library functions
• User-defined functions

Four different types of function calls.

• Function with arguments and with return value.
• Function with arguments and without return value
• Function without arguments and with return value
• Function without arguments and without return value