PHP functions
PHP functions are similar to other programming languages.
• A function is a piece of code which takes one more input in the form of parameter and
does some processing and returns a value.
• There are two parts which should be clear to you:
o Creating a PHP Function
o Calling a PHP Function
• In fact you hardly need to create your own PHP function because there are already
more than 1000 of built-in library functions created for different area and you just
need to call them according to your requirement.
Creating PHP Function:
• It is very easy to create your own PHP function.
• Suppose you want to create a PHP function which will simply write a simple message
on your browser when you will call it.
• Following example creates a function called writeMessage() and then calls it just after
creating it.
• Note that while creating a function its name should start with keyword function and all
the PHP code should be put inside { and } braces as shown in the following example
below:
<html>
<head>
<title>Writing PHP Function</title>
</head>
<body>
<?php
/* Defining a PHP Function */
function writeMessage()
{
echo "You are really a nice person, Have a nice time!";
}
/* Calling a PHP Function */
writeMessage();
?>
</body>
</html>
• This will display following result:
You are really a nice person, Have a nice time!
PHP Functions with Parameters:
• PHP gives you option to pass your parameters inside a function. You can pass as
many as parameters your like.
• These parameters work like variables inside your function.
• Following example takes two integer parameters and add them together and then
print them.
<html>
<head>
<title>Writing PHP Function with Parameters</title>
</head>
<body>
<?php
function addFunction($num1, $num2)
{
$sum = $num1 + $num2;
echo "Sum of the two numbers is : $sum";
}
$x=10;
$y=20;
addFunction($x,$y);
?>
</body>
</html>
• This will display following result:
Sum of the two numbers is : 30
Passing Arguments by Reference:
• It is possible to pass arguments to functions by reference.
• This means that a reference to the variable is manipulated by the function rather than
a copy of the variable's value.
• Any changes made to an argument in these cases will change the value of the
original variable.
• You can pass an argument by reference by adding an ampersand to the variable
name in either the function call or the function definition.
• Following example depicts both the cases.
<html>
<head>
<title>Passing Argument by Reference</title>
</head>
<body>
<?php
function addFive($num)
{
$num += 5;
}
function addSix(&$num)
{
$num += 6;
}
$orignum = 10;
addFive( &$orignum );
echo "Original Value is $orignum<br />";
addSix( $orignum );
echo "Original Value is $orignum<br />";
?>
</body>
</html>
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