PHP gets the current URL path function and server variables

1,$_server["query_string"]
Description: A string that queries (query)

2,$_server["Request_uri"]
Description: The URI required to access this page

3,$_server["script_name"]
Description: Contains the path of the current script

4,$_server[" php_self "
Description: The file name of the currently executing script

instance:
1,http://www.biuuu.com/   (open home page directly)
Result:
$_server[" query_string "] = "
$_server[" Request_uri "] ="/"
$_server[" script_name "] ="/index.php "
$_server[" php_self "]     ="/index.php "

2,http://www.biuuu.com/ ?p=222   (with query)
Result:
$_server[" query_string "] = "p=222"
$_server[" Request_uri ] = "/?p=222"
$_server[" script_name "] = "/index.php"
$_server[" php_self "]     ="/index.php "

3,http://www.biuuu.com/ index.php?p=222&q=biuuu
Result:
$_server[" query_string "] = "p=222&q=biuuu"
$_server[" Request_uri ] = "/index.php?p=222&q=biuuu"
$_server[" script_name "] = "/index.php"
$_ server[" php_self "]     = "/index.php"

$_server["query_string "] Gets the query statement, in the instance, gets the following value
$_server["script_ NAME "] gets the path to the current script, such as: index.php
$_server[" php_self "] The file name of the currently executing script