Chapter 2 External Variables, environment variables, and expressions of PHP

Chapter 2 External Variables, environment variables, expressions of 3PHP 1. external variables $ _ GET, $ _ POST, $ _ REQUEST $ _ FILES, $ _ COOKIE, $ _ SESSIONprint_r ($ _ GET ); // print all submitted forms with the name attribute value echo $ _ GET ["username"]; echo Chapter 2 2/3 PHP external variables, environment variables, expressions
1. external variables
$ _ GET, $ _ POST, and $ _ REQUEST
$ _ FILES, $ _ COOKIE, and $ _ SESSION

Print_r ($ _ GET); // print all submitted forms that contain the value of the name attribute
Echo $ _ GET ["username"];
Echo $ _ POST ["username"];
Or
Echo $ username; // whether it is post or get, you can directly add the variable name with $
2. environment variables
$ _ SERVER and $ _ ENV
Print_r ($ _ SERVER );
Echo $ _ SERVER ["remote_addr"]; // Obtain the client address
Echo $ _ SERVER ["DOCUMENT_ROOT"]; // working directory
Echo $ _ SERVER ["SCRIPT_FILENAME"]; // Current script name
Print_r ($ _ ENV); // All values are included in phpinfo ().