PHP Functions

The real power of PHP comes from its functions.

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

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

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

Create a PHP Function

A function is a block of code that can be executed whenever we need it.

Creating PHP functions:

All functions start with the word "function()"
Name the function - It should be possible to understand what the function does by its name. The name can start with a letter or underscore (not a number)
Add a "{" - The function code starts after the opening curly brace
Insert the function code
Add a "}" - The function is finished by a closing curly brace

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

<html>

<body>

<?php

function writeMyName()

  echo "Kai Jim Refsnes";

writeMyName();

?>

</body>

</html>

Now we will use the function in a PHP script:

<html>

<body>

<?php

function writeMyName()

  echo "Kai Jim Refsnes";

echo "Hello world!<br />";

echo "My name is ";

writeMyName();

echo ".<br />That's right, ";

writeMyName();

echo " is my name.";

?>

</body>

</html>

The output of the code above will be:

Hello world!

My name is Kai Jim Refsnes.

That's right, Kai Jim Refsnes is my name.

Our first function (writeMyName()) is a very simple function. It only writes a static string.

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

You may have noticed the parentheses after the function name, like: writeMyName(). The parameters are specified inside the parentheses.

The following example will write different first names, but the same last name:

<html>

<body>

<?php

function writeMyName($fname)

  echo $fname . " Refsnes.<br />";

echo "My name is ";

writeMyName("Kai Jim");

echo "My name is ";

writeMyName("Hege");

echo "My name is ";

writeMyName("Stale");

?>

</body>

</html>

The output of the code above will be:

My name is Kai Jim Refsnes.

My name is Hege Refsnes.

My name is Stale Refsnes.

The following function has two parameters:

<html>

<body>

<?php

function writeMyName($fname,$punctuation)

  echo $fname . " Refsnes" . $punctuation . "<br />";

echo "My name is ";

writeMyName("Kai Jim",".");

echo "My name is ";

writeMyName("Hege","!");

echo "My name is ";

writeMyName("Ståle","...");

?>

</body>

</html>

The output of the code above will be:

My name is Kai Jim Refsnes.

My name is Hege Refsnes!

My name is Ståle Refsnes...

Functions can also be used to return values.

<html>

<body>

<?php

function add($x,$y)

  $total = $x + $y;

  return $total;

echo "1 + 16 = " . add(1,16)

?>

</body>

</html>

The output of the code above will be:

1 + 16 = 17