PHP Functions

The real power of PHP comes from its functions.

In PHP - there are more than 700 built-in functions available.
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.
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();
?>





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.


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...


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