Solve common reasons why PHP get_include_path() returns empty values

One of the most common reasons is that the include_path in the PHP configuration file is set to empty. include_path is a configuration option for PHP that defines the path to PHP to find the included files. If this path is set to empty, PHP has no directory to look up, so a null value is returned when calling get_include_path() .

Solution : Check the include_path setting in the PHP configuration file php.ini to make sure it is not set to empty. It can be modified by:

 include_path = ".:/path/to/your/includes"

Or dynamically set include_path through PHP code:

 set_include_path('/path/to/your/includes');

2. The path was not explicitly set before using get_include_path()

If the path is not included via php.ini or set_include_path() , get_include_path() may return a null value, especially in some PHP environments. For example, some server configurations may not have default path settings.

Solution : Before using get_include_path() , you can manually set the include path through the set_include_path() function to ensure that get_include_path() can return the correct value.

 set_include_path('/path/to/your/includes');
echo get_include_path();

3. The code runs in CLI mode

When PHP is running in command line interface (CLI) mode, the return value of get_include_path() may be empty because PHP in CLI mode does not have a configuration file, or the include_path in the configuration file is incorrect. In this case, PHP will try to use the default path, but if there is no default path, it will return a null value.

Solution : When running in CLI mode, make sure to manually set include_path via command line parameters or PHP scripts.

 set_include_path('/path/to/your/includes');
echo get_include_path();

4. File permission issues

If the PHP runtime environment does not have permission to read some directories, get_include_path() may not return the included path, especially if the path setting of the configuration file is wrong, or the relevant directory does not have correct access permissions.

Solution : Check the permissions of files and directories to ensure that PHP can access the relevant file paths.

 chmod 755 /path/to/your/includes

5. Dynamically modify include_path but not updated

Sometimes the program dynamically modify include_path during running, but if it is not updated correctly, it may also return a null value when calling get_include_path() . This usually occurs after several modifications to include_path , and some modifications do not take effect.

Solution : Make sure that after each modification of include_path , the relevant path has been updated before calling get_include_path() .

 set_include_path('/path/to/your/includes');
echo get_include_path(); // Make sure it has been updated

6. Incorrect php.ini configuration file path

If PHP cannot find the correct php.ini configuration file, or the configuration file's path is not set correctly, get_include_path() may also fail to return the correct path. PHP will use built-in path settings by default. If the correct configuration file is not found, the path may be empty.

Solution : Make sure the php.ini configuration file path is correct and the file exists. You can view the location of the current PHP configuration file through the phpinfo() function:

 phpinfo();