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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 "Kai Jim Refsnes"; } echo "My name is "; writeName(); ?> </body> </html> |
Output:
| My name is Kai Jim Refsnes |
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 1
The following example will write different first names, but equal last name:
| <html> <body> <?php function writeName($fname) { echo $fname . " Refsnes.<br />"; } echo "My name is "; writeName("Kai Jim"); echo "My sister's name is "; writeName("Hege"); echo "My brother's name is "; writeName("Stale"); ?> </body> </html> |
Output:
| My name is Kai Jim Refsnes. My sister's name is Hege Refsnes. My brother's name is Stale Refsnes. |
Example 2
The following function has two parameters:
| <html> <body> <?php function writeName($fname,$punctuation) { echo $fname . " Refsnes" . $punctuation . "<br />"; } echo "My name is "; writeName("Kai Jim","."); echo "My sister's name is "; writeName("Hege","!"); echo "My brother's name is "; writeName("Ståle","?"); ?> </body> </html> |
Output:
| My name is Kai Jim Refsnes. My sister's name is Hege Refsnes! My brother's name is Ståle Refsnes? |
PHP Functions - Return values
To let a function return a value, use the return statement.
Example
| <html> <body> <?php function add($x,$y) { $total=$x+$y; return $total; } echo "1 + 16 = " . add(1,16); ?> </body> </html> |
Output:
| 1 + 16 = 17 |
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