In-depth study of PHP function checking methods available

Source: Internet
Author: User
Tags imap

We are using

PHP check function availability 1. Get all available modules-get_loaded_extensions
This function returns all loaded (available) modules.

Usage:

Print_r (get_loaded_extensions ());

PHP check function available 2. Get the available function of the specified module-get_extension_funcs
This function returns all available functions of the specified module. The input parameter (Module name) must be in lowercase.

Usage:

Print_r (get_extension_funcs ("gd "));

PHP check function available 3. Get all defined functions-get_defined_functions
This function returns all defined functions, including built-in functions and user-defined functions.

Usage:

 
 
  1. function myrow($id, $data){   
  2. return "<tr><th>$id</th><td>$data</td></tr>n";   
  3. }   
  4. $arr = get_defined_functions();   
  5. print_r($arr);   

Output:

 
 
  1. Array   
  2. (   
  3. [internal] => Array   
  4. (   
  5. [0] => zend_version   
  6. [1] => func_num_args   
  7. [2] => func_get_arg   
  8. [3] => func_get_args   
  9. [4] => strlen   
  10. [5] => strcmp   
  11. [6] => strncmp   
  12. ...   
  13. [750] => bcscale   
  14. [751] => bccomp   
  15. )   
  16. [user] => Array   
  17. (   
  18. [0] => myrow   
  19. )   
  20. )  

$ Arr ["internal"] is a built-in function, and $ arr ["user"] is a user-defined function.

PHP check function availability 4. Check whether the specified function exists-function_exists

This function returns whether the specified function has been defined.

Usage:

 
 
  1. if (function_exists('imap_open')) {   
  2. echo "IMAP functions are available.<br />n";   
  3. } else {   
  4. echo "IMAP functions are not available.<br />n";  

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