Skip to main content
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, follow these steps:
  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";
    }
?>
  1. Save the file as function.php or something similar.
  2. Upload the file to your public_html directory.
  3. 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.