PHP Functions

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The real power of PHP comes from its functions.

In PHP, there are more than 700 built-in functions.

PHP Built-in Functions

For a complete reference and examples of the built-in functions, please visit our PHP Reference.

PHP Functions

In this chapter we will show you how to create your own functions.

To keep the script from being executed when the page loads, you can put it into a function.

A function will be executed by a call to the function.

You may call a function from anywhere within a page.

Create a PHP Function

A function will be executed by a call to the function.

Syntax

function functionName()
{
code to be executed;
}

PHP function guidelines:

  • Give the function a name that reflects what the function does
  • The function name can start with a letter or underscore (not a number)

Example

A simple function that writes my name when it is called:

<html>
<body>

<?php
function writeName()
{
echo "Guru Dharsan";
}

echo "My name is ";
writeName();
?>

</body>
</html>

Output:

My name is Guru Dharsan

PHP Functions - Adding parameters

To add more functionality to a function, we can add parameters. A parameter is just like a variable.

Parameters are specified after the function name, inside the parentheses.

Example

The Below example will write different first names, but equal last name:

<html>
<body>

<?php
function writeName($fname)
{
echo $fname . " Guru.<br />";
}

echo "My name is ";
writeName("Guru");
echo "My sister's name is ";
writeName("Aishwarya");
echo "My brother's name is ";
writeName("Manu");
?>

</body>
</html>

Output:

My name is Guru Dharsan.
My sister's name is Guru Dharsan.
My brother's name is Manu Guru.

Example

The Below function has two parameters:

<html>
<body>

<?php
function writeName($fname,$punctuation)
{
echo $fname . " Guru" . $punctuation . "<br />";
}

echo "My name is ";
writeName("Guru",".");
echo "My sister's name is ";
writeName("Aishwarya","!");
echo "My brother's name is ";
writeName("Manu","?");
?>

</body>
</html>

Output:

My name is Guru Dharsan.
My sister's name is Guru Dharsan!
My brother's name is Manu Guru?
 

PHP Functions - Return values

To let a function return a value, use the return statement.

Example

<html>
<body>

<?php
function add($x,$y)
{
$total=$x+$y;
return $total;
}

echo "1 + 16 = " . add(1,16);
?>

</body>
</html>

Output:

1 + 16 = 17

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