Introduction to Functions

Real power of PHP Comes from it's bult-in functions, which are more then 1000.

PHP User-defined Functions

  • A function is a block of statements which can be used many times in a program.
  • A function will not execute until you will call.
  • A function will not execute on page load until you will call.

User Defined Function Syntax


<?php

function functionname(){
	//code goes here.
	//.
	//.
	//.
}
?>

Function Example


<?php

function Welcome(){
	echo 'Welcome to PHPDocs.com';
}
Welcome(); //calling the function

?>

Function with Parameters Example


<?php

function Sum($value1,$value2){
	echo $value1+$value2;
	echo "<br />";
}

Sum(20,30); //it will show 50
Sum(30,50); //it will show 80
Sum(40,60); //it will show 100
?>

Function with Return Example


<?php

function Multiply($value1,$value2){
	return $value1*$value2;
}

echo Multiply(2,5)."<br />; //it will show 10
echo Multiply(3,6)."<br />; //it will show 18
echo Multiply(4,8)."<br />; //it will show 32
?>

Function Parameters By Reference Example

To allow a function to modify its arguments, they must be passed by reference

place the & sign in the start of paraemeter to get Parameter by Ref


<?php

function Increment(&$value){
	++$Value
}

$counter=0;

Increment($counter); //it will show 1
Increment($counter); //it will show 2
Increment($counter); //it will show 3
Increment($counter); //it will show 4

?>