How to determine if a PHP function is available

This article describes how to use the function_exists() function to determine whether or not a function is available for your PHP installation.

Determining if a PHP function is available

You can determine whether or not a PHP function is enabled for your web site by using the function_exists() function.

To determine if a function is available:

1. Create a file that contains the following code. This sample code checks to see if the fsockopen() function is available. To check for another function, change the $function_name variable's value:

   <?php
       $function_name = "fsockopen";
       if ( function_exists($function_name ) ) {
           echo "$function_name  is enabled";
       }
       else {
           echo "$function_name  is not enabled";
       }
   ?>
   

2. Save the file as function.php or something similar.
3. Upload the file to your public_html directory.
4. Use your browser to go to http://example.com/function.php, where example.com represents your web site's domain name. The page displays whether or not the function is enabled for your web site.

More Information

For more information about the function_exists() function, please visit http://us3.php.net/manual/en/function.function-exists.php.