Usage of _ FILE _, dirname, and basename in PHP

In php, the complete path and FILE name of the current running FILE are _ FILE _. if it is used in the included FILE, the included FILE name is returned, this is a magic variable (a predefined constant). we can use dirname and basename to obtain the file directory or... in php, the complete path and FILE name of the current running FILE are _ FILE _. if it is used in the included FILE, the included FILE name is returned, this is a magic variable (a predefined constant). we can use dirname and basename to obtain the file directory or file name.

1. use _ FILE _ and dirname (_ FILE _) and basename (_ FILE:

It is usually very effective to use dirname (_ FILE _) when configuring the FILE path, however, because the path of _ FILE _ is the complete path of the FILE where the current code is located (rather than the FILE where the url is located), the configuration FILE must be defined under the root directory to define the root address of the website, however, the following method can solve the problem of storing the configuration file:

Dirname (_ FILE __));

Assume that _ FILE _ is/home/web/config. php, and the above method output is/home/web

Dirname (_ FILE _); the directory name at the top of the FILE is obtained.

Dirname (_ FILE _); the directory name of the FILE's layer is obtained.

Assume that the current directory and file structure are as follows. the variables we want to test are in the wp_smtp_admin.php file:

Wp-content \ plugins \ wp-smtp \ wp-smtp.php

Wp-content \ plugins \ wp-smtp \ wp_smtp_admin.php

Wp-content \ plugins \ wp-smtp \ img \ blq_32_32.jpg

The test result is as follows:

Echo _ FILE __."
"; // Output F: \ xampp \ htdocs \ wordpress \ wp-content \ plugins \ wp-smtp \ wp_smtp_admin.php echo dirname (_ FILE __)."
"; // Output F: \ xampp \ htdocs \ wordpress \ wp-content \ plugins \ wp-smtp echo basename (_ FILE __)."
"; // Output wp_smtp_admin.php

2. test some built-in functions of wordpress: // www.phprm.com

Echo plugin_basename (_ FILE __)."
"; // Output wp-smtp/wp_smtp_admin.php echo dirname (plugin_basename (_ FILE __))."
"; // Output wp-smtp echo plugin_dir_url (_ FILE __)."
"; // Output http: // localhost/wordpress/wp-content/plugins/wp-smtp/echo plugin_dir_path (_ FILE __)."
"; // Output F: \ xampp \ htdocs \ wordpress \ wp-content \ plugins \ wp-smtp/echo plugins_url ()."
"; // Output http: // localhost/wordpress/wp-content/plugins echo plugins_url ('' ,__ FILE __)."
"; // Output http: // localhost/wordpress/wp-content/plugins/wp-smtp echo plugins_url ('' ,__ FILE __)."
"; // Output http: // localhost/wordpress/wp-content/plugins/wp-smtp/img/blq_32_32.jpg

Now let's take a look at the dirname and basename descriptions.

The dirname () function returns the directory part of the path, while the basename () function returns the file name part of the path. from here, we can easily see the above result.