PHP Functions

The real power of PHP comes from its functions.

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


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PHP Functions
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.


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


function writeMyName()
{
echo "Kai Jim Refsnes";
}writeMyName();
?>



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Use a PHP Function
Now we will use the function in a PHP script:


function writeMyName()
{
echo "Kai Jim Refsnes";
}echo "Hello world!
";
echo "My name is ";
writeMyName();
echo ".
That's right, ";
writeMyName();
echo " is my name.";
?>


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.


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PHP Functions - Adding parameters
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.

Example 1
The following example will write different first names, but the same last name:


function writeMyName($fname)
{
echo $fname . " Refsnes.
";
}echo "My name is ";
writeMyName("Kai Jim");echo "My name is ";
writeMyName("Hege");echo "My name is ";
writeMyName("Stale");
?>


The output of the code above will be:

My name is Kai Jim Refsnes.
My name is Hege Refsnes.
My name is Stale Refsnes.

Example 2
The following function has two parameters:


function writeMyName($fname,$punctuation)
{
echo $fname . " Refsnes" . $punctuation . "
";
}echo "My name is ";
writeMyName("Kai Jim",".");echo "My name is ";
writeMyName("Hege","!");echo "My name is ";
writeMyName("Ståle","...");
?>


The output of the code above will be:

My name is Kai Jim Refsnes.
My name is Hege Refsnes!
My name is Ståle Refsnes...

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PHP Functions - Return values
Functions can also be used to return values.

Example

function add($x,$y)
{
$total = $x + $y;
return $total;
}echo "1 + 16 = " . add(1,16);
?>


The output of the code above will be:

1 + 16 = 17