Php functions for obtaining the current url path

Php: function used to obtain the current url path. PHP: QUERY_STRING, REQUEST_URI, and SCRIPT .. PHP obtains the functions and server variables of the current url path: QUERY_STRING, REQUEST_URI, SCRIPT ..??? Php code ?? $ _ SER function for php to obtain the current url path

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Functions for PHP to obtain the current url path: QUERY_STRING, REQUEST_URI, SCRIPT... PHP to obtain the current url path functions and server variables: QUERY_STRING, REQUEST_URI, SCRIPT ..?
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Php code ??

1. $ _ SERVER ["QUERY_STRING"]: obtain the query statement. Which of the following statements can be obtained in the instance? The following value ??
2. $ _ SERVER ["REQUEST_URI"]? Obtain the value after http: // 172.16.1.7, including /??
3. $ _ SERVER ["SCRIPT_NAME"]? Obtain the path of the current script, such as jms. php ??
4. $ _ SERVER ["PHP_SELF"]? File name of the script being executed ??