PHP provides a large number of predefined variables to all scripts. The variables represent everything from external variables to built-in environment variables, last error messages to last retrieved headers.
See also the FAQ titled "How does register_globals affect me?"
Superglobals — Superglobals are built-in variables that are always available in all scopes
Several predefined variables in PHP are "superglobals", which means they are available in all scopes throughout a script. There is no need to do global $variable; to access them within functions or methods.
These superglobal variables are:
| 版本 | 说明 |
|---|---|
| 4.1.0 | Superglobals were introduced to PHP. |
Note: Variable availability
By default, all of the superglobals are available but there are directives that affect this availability. For further information, refer to the documentation for variables_order.
Note: Dealing with register_globals
If the deprecated register_globals directive is set to on then the variables within will also be made available in the global scope of the script. For example, $_POST['foo'] would also exist as $foo.
For related information, see the FAQ titled "How does register_globals affect me?"
Note: Variable variables
Superglobals cannot be used as variable variables inside functions or class methods.
Superglobals -- $GLOBALS — References all variables available in global scope
An associative array containing references to all variables which are currently defined in the global scope of the script. The variable names are the keys of the array.
Example #1 $GLOBALS example
<?php
function test() {
$foo = "local variable";
echo '$foo in global scope: ' . $GLOBALS["foo"] . "\n";
echo '$foo in current scope: ' . $foo . "\n";
}
$foo = "Example content";
test();
?>
上例的输出类似于：
$foo in global scope: Example content $foo in current scope: local variable
Note: This is a 'superglobal', or automatic global, variable. This simply means that it is available in all scopes throughout a script. There is no need to do global $variable; to access it within functions or methods.
Note: Variable availability
Unlike all of the other superglobals, $GLOBALS has essentially always been available in PHP.
Superglobals -- $GLOBALS -- $_SERVER -- $HTTP_SERVER_VARS [deprecated] — Server and execution environment information
$_SERVER is an array containing information such as headers, paths, and script locations. The entries in this array are created by the web server. There is no guarantee that every web server will provide any of these; servers may omit some, or provide others not listed here. That said, a large number of these variables are accounted for in the » CGI 1.1 specification, so you should be able to expect those.
$HTTP_SERVER_VARS contains the same initial information, but is not a superglobal. (Note that $HTTP_SERVER_VARS and $_SERVER are different variables and that PHP handles them as such)
You may or may not find any of the following elements in $_SERVER. Note that few, if any, of these will be available (or indeed have any meaning) if running PHP on the command line.
Note: PHP script is terminated after sending headers (it means after producing any output without output buffering) if the request method was HEAD.
Note: Note that when using ISAPI with IIS, the value will be off if the request was not made through the HTTPS protocol.
Note: Your web server must be configured to create this variable. For example in Apache you'll need HostnameLookups On inside httpd.conf for it to exist. See also gethostbyaddr().
The absolute pathname of the currently executing script.
Note: If a script is executed with the CLI, as a relative path, such as file.php or ../file.php, $_SERVER['SCRIPT_FILENAME'] will contain the relative path specified by the user.
Note: As of PHP 4.3.2, PATH_TRANSLATED is no longer set implicitly under the Apache 2 SAPI in contrast to the situation in Apache 1, where it's set to the same value as the SCRIPT_FILENAME server variable when it's not populated by Apache. This change was made to comply with the CGI specification that PATH_TRANSLATED should only exist if PATH_INFO is defined. Apache 2 users may use AcceptPathInfo = On inside httpd.conf to define PATH_INFO.
| 版本 | 说明 |
|---|---|
| 4.1.0 | Introduced $_SERVER that deprecated $HTTP_SERVER_VARS. |
Example #2 $_SERVER example
<?php
echo $_SERVER['SERVER_NAME'];
?>
上例的输出类似于：
www.example.com
Note: This is a 'superglobal', or automatic global, variable. This simply means that it is available in all scopes throughout a script. There is no need to do global $variable; to access it within functions or methods.
Superglobals -- $GLOBALS -- $_SERVER -- $HTTP_SERVER_VARS [deprecated] -- $_GET -- $HTTP_GET_VARS [deprecated] — HTTP GET variables
An associative array of variables passed to the current script via the HTTP GET method.
$HTTP_GET_VARS contains the same initial information, but is not a superglobal. (Note that $HTTP_GET_VARS and $_GET are different variables and that PHP handles them as such)
| 版本 | 说明 |
|---|---|
| 4.1.0 | Introduced $_GET that deprecated $HTTP_GET_VARS. |
Example #3 $_GET example
<?php
echo 'Hello ' . htmlspecialchars($_GET["name"]) . '!';
?>
Assuming the user entered http://example.com/?name=Hannes
上例的输出类似于：
Hello Hannes!
Note: This is a 'superglobal', or automatic global, variable. This simply means that it is available in all scopes throughout a script. There is no need to do global $variable; to access it within functions or methods.
Superglobals -- $GLOBALS -- $_SERVER -- $HTTP_SERVER_VARS [deprecated] -- $_GET -- $HTTP_GET_VARS [deprecated] -- $_POST -- $HTTP_POST_VARS [deprecated] — HTTP POST variables
An associative array of variables passed to the current script via the HTTP POST method.
$HTTP_POST_VARS contains the same initial information, but is not a superglobal. (Note that $HTTP_POST_VARS and $_POST are different variables and that PHP handles them as such)
| 版本 | 说明 |
|---|---|
| 4.1.0 | Introduced $_POST that deprecated $HTTP_POST_VARS. |
Example #4 $_POST example
<?php
echo 'Hello ' . htmlspecialchars($_POST["name"]) . '!';
?>
Assuming the user POSTed name=Hannes
上例的输出类似于：
Hello Hannes!
Note: This is a 'superglobal', or automatic global, variable. This simply means that it is available in all scopes throughout a script. There is no need to do global $variable; to access it within functions or methods.
Superglobals -- $GLOBALS -- $_SERVER -- $HTTP_SERVER_VARS [deprecated] -- $_GET -- $HTTP_GET_VARS [deprecated] -- $_POST -- $HTTP_POST_VARS [deprecated] -- $_FILES -- $HTTP_POST_FILES [deprecated] — HTTP File Upload variables
An associative array of items uploaded to the current script via the HTTP POST method.
$HTTP_POST_FILES contains the same initial information, but is not a superglobal. (Note that $HTTP_POST_FILES and $_FILES are different variables and that PHP handles them as such)
| 版本 | 说明 |
|---|---|
| 4.1.0 | Introduced $_FILES that deprecated $HTTP_POST_FILES. |
Note: This is a 'superglobal', or automatic global, variable. This simply means that it is available in all scopes throughout a script. There is no need to do global $variable; to access it within functions or methods.
Superglobals -- $GLOBALS -- $_SERVER -- $HTTP_SERVER_VARS [deprecated] -- $_GET -- $HTTP_GET_VARS [deprecated] -- $_POST -- $HTTP_POST_VARS [deprecated] -- $_FILES -- $HTTP_POST_FILES [deprecated] -- $_REQUEST — HTTP Request variables
| 版本 | 说明 |
|---|---|
| 5.3.0 | Introduced request_order. This directive affects the contents of $_REQUEST. |
| 4.3.0 | $_FILES information was removed from $_REQUEST. |
| 4.1.0 | Introduced $_REQUEST. |
Note: This is a 'superglobal', or automatic global, variable. This simply means that it is available in all scopes throughout a script. There is no need to do global $variable; to access it within functions or methods.
Note: When running on the command line , this will not include the argv and argc entries; these are present in the $_SERVER array.
Note: The variables in $_REQUEST are provided to the script via the GET, POST, and COOKIE input mechanisms and therefore could be modified by the remote user and cannot be trusted. The presence and order of variables listed in this array is defined according to the PHP variables_order configuration directive.
Superglobals -- $GLOBALS -- $_SERVER -- $HTTP_SERVER_VARS [deprecated] -- $_GET -- $HTTP_GET_VARS [deprecated] -- $_POST -- $HTTP_POST_VARS [deprecated] -- $_FILES -- $HTTP_POST_FILES [deprecated] -- $_REQUEST -- $_SESSION -- $HTTP_SESSION_VARS [deprecated] — Session variables
An associative array containing session variables available to the current script. See the Session functions documentation for more information on how this is used.
$HTTP_SESSION_VARS contains the same initial information, but is not a superglobal. (Note that $HTTP_SESSION_VARS and $_SESSION are different variables and that PHP handles them as such)
| 版本 | 说明 |
|---|---|
| 4.1.0 | Introduced $_SESSION that deprecated $HTTP_SESSION_VARS. |
Note: This is a 'superglobal', or automatic global, variable. This simply means that it is available in all scopes throughout a script. There is no need to do global $variable; to access it within functions or methods.
Superglobals -- $GLOBALS -- $_SERVER -- $HTTP_SERVER_VARS [deprecated] -- $_GET -- $HTTP_GET_VARS [deprecated] -- $_POST -- $HTTP_POST_VARS [deprecated] -- $_FILES -- $HTTP_POST_FILES [deprecated] -- $_REQUEST -- $_SESSION -- $HTTP_SESSION_VARS [deprecated] -- $_ENV -- $HTTP_ENV_VARS [deprecated] — Environment variables
An associative array of variables passed to the current script via the environment method.
These variables are imported into PHP's global namespace from the environment under which the PHP parser is running. Many are provided by the shell under which PHP is running and different systems are likely running different kinds of shells, a definitive list is impossible. Please see your shell's documentation for a list of defined environment variables.
Other environment variables include the CGI variables, placed there regardless of whether PHP is running as a server module or CGI processor.
$HTTP_ENV_VARS contains the same initial information, but is not a superglobal. (Note that $HTTP_ENV_VARS and $_ENV are different variables and that PHP handles them as such)
| 版本 | 说明 |
|---|---|
| 4.1.0 | Introduced $_ENV that deprecated $HTTP_ENV_VARS. |
Example #5 $_ENV example
<?php
echo 'My username is ' .$_ENV["USER"] . '!';
?>
Assuming "bjori" executes this script
上例的输出类似于：
My username is bjori!
Note: This is a 'superglobal', or automatic global, variable. This simply means that it is available in all scopes throughout a script. There is no need to do global $variable; to access it within functions or methods.
Superglobals -- $GLOBALS -- $_SERVER -- $HTTP_SERVER_VARS [deprecated] -- $_GET -- $HTTP_GET_VARS [deprecated] -- $_POST -- $HTTP_POST_VARS [deprecated] -- $_FILES -- $HTTP_POST_FILES [deprecated] -- $_REQUEST -- $_SESSION -- $HTTP_SESSION_VARS [deprecated] -- $_ENV -- $HTTP_ENV_VARS [deprecated] -- $_COOKIE -- $HTTP_COOKIE_VARS [deprecated] -- $php_errormsg — The previous error message
$php_errormsg is a variable containing the text of the last error message generated by PHP. This variable will only be available within the scope in which the error occurred, and only if the track_errors configuration option is turned on (it defaults to off).
Note: This variable is only available when track_errors is enabled in php.ini.
If a user defined error handler is set $php_errormsg is only set if the error handler returns FALSE
Example #7 $php_errormsg example
<?php
@strpos();
echo $php_errormsg;
?>
上例的输出类似于：
Wrong parameter count for strpos()
Superglobals -- $GLOBALS -- $_SERVER -- $HTTP_SERVER_VARS [deprecated] -- $_GET -- $HTTP_GET_VARS [deprecated] -- $_POST -- $HTTP_POST_VARS [deprecated] -- $_FILES -- $HTTP_POST_FILES [deprecated] -- $_REQUEST -- $_SESSION -- $HTTP_SESSION_VARS [deprecated] -- $_ENV -- $HTTP_ENV_VARS [deprecated] -- $_COOKIE -- $HTTP_COOKIE_VARS [deprecated] -- $php_errormsg -- $HTTP_RAW_POST_DATA — Raw POST data
$HTTP_RAW_POST_DATA contains the raw POST data. See always_populate_raw_post_data
Superglobals -- $GLOBALS -- $_SERVER -- $HTTP_SERVER_VARS [deprecated] -- $_GET -- $HTTP_GET_VARS [deprecated] -- $_POST -- $HTTP_POST_VARS [deprecated] -- $_FILES -- $HTTP_POST_FILES [deprecated] -- $_REQUEST -- $_SESSION -- $HTTP_SESSION_VARS [deprecated] -- $_ENV -- $HTTP_ENV_VARS [deprecated] -- $_COOKIE -- $HTTP_COOKIE_VARS [deprecated] -- $php_errormsg -- $HTTP_RAW_POST_DATA -- $http_response_header — HTTP response headers
The $http_response_header array is similar to the get_headers() function. When using the HTTP wrapper, $http_response_header will be populated with the HTTP response headers.
Example #8 $http_response_header example
<?php
file_get_contents("http://example.com");
var_dump($http_response_header);
?>
上例的输出类似于：
array(9) {
[0]=>
string(15) "HTTP/1.1 200 OK"
[1]=>
string(35) "Date: Sat, 12 Apr 2008 17:30:38 GMT"
[2]=>
string(29) "Server: Apache/2.2.3 (CentOS)"
[3]=>
string(44) "Last-Modified: Tue, 15 Nov 2005 13:24:10 GMT"
[4]=>
string(27) "ETag: "280100-1b6-80bfd280""
[5]=>
string(20) "Accept-Ranges: bytes"
[6]=>
string(19) "Content-Length: 438"
[7]=>
string(17) "Connection: close"
[8]=>
string(38) "Content-Type: text/html; charset=UTF-8"
}
Superglobals -- $GLOBALS -- $_SERVER -- $HTTP_SERVER_VARS [deprecated] -- $_GET -- $HTTP_GET_VARS [deprecated] -- $_POST -- $HTTP_POST_VARS [deprecated] -- $_FILES -- $HTTP_POST_FILES [deprecated] -- $_REQUEST -- $_SESSION -- $HTTP_SESSION_VARS [deprecated] -- $_ENV -- $HTTP_ENV_VARS [deprecated] -- $_COOKIE -- $HTTP_COOKIE_VARS [deprecated] -- $php_errormsg -- $HTTP_RAW_POST_DATA -- $http_response_header -- $argc — The number of arguments passed to script
Contains the number of arguments passed to the current script when running from the command line.
Note: The script's filename is always passed as an argument to the script, therefore the minimum value of $argc is 1.
Note: This variable is only available when register_argc_argv is enabled.
Example #9 $argc example
<?php
var_dump($argc);
?>
When executing the example with: php script.php arg1 arg2 arg3
上例的输出类似于：
int(4)
Superglobals -- $GLOBALS -- $_SERVER -- $HTTP_SERVER_VARS [deprecated] -- $_GET -- $HTTP_GET_VARS [deprecated] -- $_POST -- $HTTP_POST_VARS [deprecated] -- $_FILES -- $HTTP_POST_FILES [deprecated] -- $_REQUEST -- $_SESSION -- $HTTP_SESSION_VARS [deprecated] -- $_ENV -- $HTTP_ENV_VARS [deprecated] -- $_COOKIE -- $HTTP_COOKIE_VARS [deprecated] -- $php_errormsg -- $HTTP_RAW_POST_DATA -- $http_response_header -- $argc -- $argv — Array of arguments passed to script
Contains an array of all the arguments passed to the script when running from the command line.
Note: The first argument is always the current script's filename, therefore $argv[0] is the script's name.
Note: This variable is only available when register_argc_argv is enabled.
Example #10 $argv example
<?php
var_dump($argv);
?>
When executing the example with: php script.php arg1 arg2 arg3
上例的输出类似于：
array(4) {
[0]=>
string(10) "script.php"
[1]=>
string(4) "arg1"
[2]=>
string(4) "arg2"
[3]=>
string(4) "arg3"
}