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.
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:
| <html> <body> <?php function writeMyName() { echo "Kai Jim Refsnes"; } writeMyName(); ?> </body> </html> |
Use a PHP Function
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! |
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:
| <html> <body> <?php function writeMyName($fname) { echo $fname . " Refsnes.<br />"; } echo "My name is "; writeMyName("Kai Jim"); echo "My name is "; writeMyName("Hege"); echo "My name is "; writeMyName("Stale"); ?> </body> </html> |
The output of the code above will be:
My name is Kai Jim Refsnes. |
Example 2
The following function has two parameters:
| <html> <body> <?php function writeMyName($fname,$punctuation) { echo $fname . " Refsnes" . $punctuation . "<br />"; } echo "My name is "; writeMyName("Kai Jim","."); echo "My name is "; writeMyName("Hege","!"); echo "My name is "; writeMyName("Ståle","..."); ?> </body> </html> |
The output of the code above will be:
My name is Kai Jim Refsnes. |
PHP Functions - Return values
Functions can also be used to return values.
Example
| <html> <body> <?php function add($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 |
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