Chapter II two/3 external variables, environment variables, expressions for PHP

Chapter II 2/3 external variables, environment variables, expressions for PHP
1. External variables
$_get, $_post, $_request
$_files, $_cookie, $_session

Print_r ($_get);//Print all submitted forms containing the value of the Name property
echo $_get["username"];
echo $_post["username"];
Or
echo $username;//Whether it is a post or get pass value, you can use the $ plus variable name directly
2. Environment variables
$_server and $_env
Print_r ($_server);
echo $_server["REMOTE_ADDR"];//get the client address
echo $_server["Document_root"];//working directory
echo $_server["Script_filename"];//Current pin name
Print_r ($_env);//All values are included in the Phpinfo ()

