ThinkPHP function description: C method

: This article mainly introduces ThinkPHP Function details: C method. if you are interested in the PHP Tutorial, refer to it. The C method is ThinkPHP's method for setting, obtaining, and saving configuration parameters, which is frequently used.
To understand the C method, you must first understand the configuration of ThinkPHP, because all operations of the C method are related to the configuration. The ThinkPHP configuration file is defined in the PHP array format.
The function overload design is used, so there are many usage instructions.
Set parameters

C('DB_NAME','thinkphp');

It indicates that the value of the DB_NAME configuration parameter is thinkphp. because the configuration parameters are case-insensitive, the following statement is the same:

C('db_name','thinkphp');

However, we recommend that you keep the configuration definition specification in uppercase.
All parameters of the project can be dynamically changed using this method before they take effect. The final value will overwrite the definitions in the previous setting or conventional configuration, you can also use the parameter configuration method to add a new configuration.
Supports second-level configuration parameter settings, for example:

C('USER.USER_ID',8);

It is not recommended that the configuration parameters exceed level 2.
If you want to set multiple parameters, you can use batch settings, for example:

$config['user_id'] = 1;$config['user_type'] = 1;C($config);

If the first parameter of the C method is input into an array, it indicates batch assignment. the above assignment is equivalent:

C('USER_ID',1);C('USER_TYPE',1);

GET parameters
To obtain the set parameters, you can use:

$userId = C('USER_ID');$userType = C('USER_TYPE');

If the USER_ID parameter has not been defined, NULL is returned.
You can also obtain second-level configuration parameters, for example:

$userId = C('USER.USER_ID');

If the input configuration parameter is null, all parameters are obtained:

$config = C();

Save Settings
Version 3.1 adds the function of permanently saving set parameters, which is only applicable to batch assignment. for example:

$config['user_id'] = 1;$config['user_type'] = 1;C($config,'name');

After the config parameters are set in batches, they are saved to the cache file (or other configuration cache methods) together with all the current configuration parameters ).
After saving, if you want to retrieve the saved parameters, you can use

$config = C('','name');

Here, name is the cache ID used to save the parameters. the saved parameters must be consistent before they can be retrieved correctly. The retrieved parameters are merged with the current configuration parameters.

The above describes the ThinkPHP Function details: C method, including some content, hope to be helpful to friends who are interested in PHP tutorials.