Introduction to Functions in PHP

In this Tutorial you'll learn about Functions in PHP. This includes - What is a Function?, How to define and call functions in PHP.

What is a Function?

A Function is a small set of statements defined by the programmer to do a specific action. They take input values in the form of 'arguments' and return values after execution. They can be written anywhere in the program. They are used to reduce the programming complexity and to handle the programming structures easily. The function takes an input, performs some operation with it and returns a value after successful execution. Functions are basically of two types, namely:

Functions with no return value
Functions with return values

How to define & call functions

Functions are defined using the keyword 'function' followed by the function name. The input parameters are listed in parentheses after the function name, followed by the function code within braces after the arguments as shown below:

Function with no return value

Syntax:

function function_name(parameters)
{
...function code..
return;
}

Example:

<?php
function Tax($salary){
$tax=($salary*33)/100;
echo "Tax for ".$salary." is :".$tax;
return;
}
Tax(3000);
?>

Output: "Tax for 3000 is :990"

In the above example we define a function called 'Tax' with '$salary' as its argument (input). We calculate the tax value using the salary and the output is displayed. Here the function returns no value.

Function with return values

Syntax:

function function_name(parameters)
{
...function code..
return(variable_name);
}

Example:

<?php
function Tax($salary){
$tax=($salary*33)/100;
return($tax);
}
$salary=3000;
$taxamount=Tax($salary);
echo "Tax for ".$salary." is :".$taxamount;
?>

Output: "Tax for 3000 is :990"

In the above example we have redefined the function 'Tax' to return a value. The returned value is assigned to the variable '$taxamount' and the output is displayed as shown above. That's it you've learnt how to use functions in PHP.

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