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PHP Manual

Predefined variables

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

SuperglobalsSuperglobals are built-in variables that are always available in all scopes

说明

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:

更新日志

版本 说明
4.1.0 Superglobals were introduced to PHP.

注释

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.

$GLOBALS

Superglobals -- $GLOBALSReferences all variables available in global scope

说明

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.

范例

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

注释

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.

$_SERVER

$HTTP_SERVER_VARS [deprecated]

Superglobals -- $GLOBALS -- $_SERVER -- $HTTP_SERVER_VARS [deprecated]Server and execution environment information

说明

$_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)

Indices

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.

'PHP_SELF'
The filename of the currently executing script, relative to the document root. For instance, $_SERVER['PHP_SELF'] in a script at the address http://example.com/test.php/foo.bar would be /test.php/foo.bar. The __FILE__ constant contains the full path and filename of the current (i.e. included) file. If PHP is running as a command-line processor this variable contains the script name since PHP 4.3.0. Previously it was not available.
'argv'
Array of arguments passed to the script. When the script is run on the command line, this gives C-style access to the command line parameters. When called via the GET method, this will contain the query string.
'argc'
Contains the number of command line parameters passed to the script (if run on the command line).
'GATEWAY_INTERFACE'
What revision of the CGI specification the server is using; i.e. 'CGI/1.1'.
'SERVER_ADDR'
The IP address of the server under which the current script is executing.
'SERVER_NAME'
The name of the server host under which the current script is executing. If the script is running on a virtual host, this will be the value defined for that virtual host.
'SERVER_SOFTWARE'
Server identification string, given in the headers when responding to requests.
'SERVER_PROTOCOL'
Name and revision of the information protocol via which the page was requested; i.e. 'HTTP/1.0';
'REQUEST_METHOD'
Which request method was used to access the page; i.e. 'GET', 'HEAD', 'POST', 'PUT'.

Note: PHP script is terminated after sending headers (it means after producing any output without output buffering) if the request method was HEAD.

'REQUEST_TIME'
The timestamp of the start of the request. Available since PHP 5.1.0.
'QUERY_STRING'
The query string, if any, via which the page was accessed.
'DOCUMENT_ROOT'
The document root directory under which the current script is executing, as defined in the server's configuration file.
'HTTP_ACCEPT'
Contents of the Accept: header from the current request, if there is one.
'HTTP_ACCEPT_CHARSET'
Contents of the Accept-Charset: header from the current request, if there is one. Example: 'iso-8859-1,*,utf-8'.
'HTTP_ACCEPT_ENCODING'
Contents of the Accept-Encoding: header from the current request, if there is one. Example: 'gzip'.
'HTTP_ACCEPT_LANGUAGE'
Contents of the Accept-Language: header from the current request, if there is one. Example: 'en'.
'HTTP_CONNECTION'
Contents of the Connection: header from the current request, if there is one. Example: 'Keep-Alive'.
'HTTP_HOST'
Contents of the Host: header from the current request, if there is one.
'HTTP_REFERER'
The address of the page (if any) which referred the user agent to the current page. This is set by the user agent. Not all user agents will set this, and some provide the ability to modify HTTP_REFERER as a feature. In short, it cannot really be trusted.
'HTTP_USER_AGENT'
Contents of the User-Agent: header from the current request, if there is one. This is a string denoting the user agent being which is accessing the page. A typical example is: Mozilla/4.5 [en] (X11; U; Linux 2.2.9 i586). Among other things, you can use this value with get_browser() to tailor your page's output to the capabilities of the user agent.
'HTTPS'
Set to a non-empty value if the script was queried through the HTTPS protocol.

Note: Note that when using ISAPI with IIS, the value will be off if the request was not made through the HTTPS protocol.

'REMOTE_ADDR'
The IP address from which the user is viewing the current page.
'REMOTE_HOST'
The Host name from which the user is viewing the current page. The reverse dns lookup is based off the REMOTE_ADDR of the user.

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().

'REMOTE_PORT'
The port being used on the user's machine to communicate with the web server.
'SCRIPT_FILENAME'

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.

'SERVER_ADMIN'
The value given to the SERVER_ADMIN (for Apache) directive in the web server configuration file. If the script is running on a virtual host, this will be the value defined for that virtual host.
'SERVER_PORT'
The port on the server machine being used by the web server for communication. For default setups, this will be '80'; using SSL, for instance, will change this to whatever your defined secure HTTP port is.
'SERVER_SIGNATURE'
String containing the server version and virtual host name which are added to server-generated pages, if enabled.
'PATH_TRANSLATED'
Filesystem- (not document root-) based path to the current script, after the server has done any virtual-to-real mapping.

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.

'SCRIPT_NAME'
Contains the current script's path. This is useful for pages which need to point to themselves. The __FILE__ constant contains the full path and filename of the current (i.e. included) file.
'REQUEST_URI'
The URI which was given in order to access this page; for instance, '/index.html'.
'PHP_AUTH_DIGEST'
When running under Apache as module doing Digest HTTP authentication this variable is set to the 'Authorization' header sent by the client (which you should then use to make the appropriate validation).
'PHP_AUTH_USER'
When running under Apache or IIS (ISAPI on PHP 5) as module doing HTTP authentication this variable is set to the username provided by the user.
'PHP_AUTH_PW'
When running under Apache or IIS (ISAPI on PHP 5) as module doing HTTP authentication this variable is set to the password provided by the user.
'AUTH_TYPE'
When running under Apache as module doing HTTP authenticated this variable is set to the authentication type.

更新日志

版本 说明
4.1.0 Introduced $_SERVER that deprecated $HTTP_SERVER_VARS.

范例

Example #2 $_SERVER example

<?php
echo $_SERVER['SERVER_NAME'];
?>

上例的输出类似于:

www.example.com

注释

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.

$_GET

$HTTP_GET_VARS [deprecated]

Superglobals -- $GLOBALS -- $_SERVER -- $HTTP_SERVER_VARS [deprecated] -- $_GET -- $HTTP_GET_VARS [deprecated]HTTP GET variables

说明

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)

更新日志

版本 说明
4.1.0 Introduced $_GET that deprecated $HTTP_GET_VARS.

范例

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!

注释

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.

$_POST

$HTTP_POST_VARS [deprecated]

Superglobals -- $GLOBALS -- $_SERVER -- $HTTP_SERVER_VARS [deprecated] -- $_GET -- $HTTP_GET_VARS [deprecated] -- $_POST -- $HTTP_POST_VARS [deprecated]HTTP POST variables

说明

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)

更新日志

版本 说明
4.1.0 Introduced $_POST that deprecated $HTTP_POST_VARS.

范例

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!

注释

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.

$_FILES

$HTTP_POST_FILES [deprecated]

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

说明

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)

更新日志

版本 说明
4.1.0 Introduced $_FILES that deprecated $HTTP_POST_FILES.

注释

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.

参见

$_REQUEST

Superglobals -- $GLOBALS -- $_SERVER -- $HTTP_SERVER_VARS [deprecated] -- $_GET -- $HTTP_GET_VARS [deprecated] -- $_POST -- $HTTP_POST_VARS [deprecated] -- $_FILES -- $HTTP_POST_FILES [deprecated] -- $_REQUESTHTTP Request variables

说明

An associative array that by default contains the contents of $_GET, $_POST$_COOKIE.

更新日志

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.

注释

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.

参见

$_SESSION

$HTTP_SESSION_VARS [deprecated]

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

说明

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)

更新日志

版本 说明
4.1.0 Introduced $_SESSION that deprecated $HTTP_SESSION_VARS.

注释

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.

参见

$_ENV

$HTTP_ENV_VARS [deprecated]

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

说明

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)

更新日志

版本 说明
4.1.0 Introduced $_ENV that deprecated $HTTP_ENV_VARS.

范例

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!

注释

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.

参见

$_COOKIE

$HTTP_COOKIE_VARS [deprecated]

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]HTTP Cookies

说明

An associative array of variables passed to the current script via HTTP Cookies.

$HTTP_COOKIE_VARS contains the same initial information, but is not a superglobal. (Note that $HTTP_COOKIE_VARS and $_COOKIE are different variables and that PHP handles them as such)

更新日志

版本 说明
4.1.0 Introduced $_COOKIE that deprecated $HTTP_COOKIE_VARS.

范例

Example #6 $_COOKIE example

<?php
echo 'Hello ' htmlspecialchars($_COOKIE["name"]) . '!';
?>

Assuming the "name" cookie has been set earlier

上例的输出类似于:

Hello Hannes!

注释

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.

$php_errormsg

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_errormsgThe previous error message

说明

$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.

Warning

If a user defined error handler is set $php_errormsg is only set if the error handler returns FALSE

范例

Example #7 $php_errormsg example

<?php
@strpos();
echo 
$php_errormsg;
?>

上例的输出类似于:

Wrong parameter count for strpos()

$HTTP_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_DATARaw POST data

说明

$HTTP_RAW_POST_DATA contains the raw POST data. See always_populate_raw_post_data

$http_response_header

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_headerHTTP response headers

说明

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.

范例

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"
}

$argc

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 -- $argcThe number of arguments passed to script

说明

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.

范例

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)

$argv

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 -- $argvArray of arguments passed to script

说明

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.

范例

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"
}


语言参考
PHP Manual
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