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PHP学习之预定义变量(实例讲解)

超全局变量–超全局变量是全部作用域中始终可用的内置变量

$GLOBALS

一个包含了全部变量的全局组合数组。变量的名字就是数组的键。

<?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(); ?> 以上例程的输出类似于: $foo in global scope: Example content $foo in current scope: local variable

$_SERVER

<?PHP echo "<pre>"; var_dump($_SERVER); output: array (size=35) 'HTTP_HOST' => string 'localhost' (length=9) 'HTTP_CONNECTION' => string 'keep-alive' (length=10) 'HTTP_UPGRADE_INSECURE_REQUESTS' => string '1' (length=1) 'HTTP_USER_AGENT' => string 'Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/53.0.2785.104 Safari/537.36 Core/1.53.3538.400 QQBrowser/9.6.12501.400' (length=153) 'HTTP_ACCEPT' => string 'text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8' (length=74) 'HTTP_REFERER' => string 'http://localhost/test/' (length=22) 'HTTP_ACCEPT_ENCODING' => string 'gzip, deflate, sdch' (length=19) 'HTTP_ACCEPT_LANGUAGE' => string 'zh-CN,zh;q=0.8' (length=14) 'PATH' => string '%APPCAN_PATH%;D:\Work\python2.7\;D:\Work\python2.7\Scripts;C:\ProgramData\Oracle\Java\javapath;C:\WINDOWS\system32;C:\WINDOWS;C:\WINDOWS\System32\Wbem;C:\WINDOWS\System32\WindowsPowerShell\v1.0\;D:\wampserver\mysql\bin;D:\Work\JAVA\tomcat\bin;D:\Work\Mozilla Firefox\firefox.exe;D:\Work\phantomjs\bin;D:\Work\chormedriver;C:\WINDOWS\system32\config\systemprofile\.dnx\bin;C:\Program Files\Microsoft DNX\Dnvm\;C:\Program Files\Microsoft SQL Server\130\Tools\Binn\;D:\wampserver\php;C:\ProgramData\ComposerSetup\bi'... (length=607) 'SystemRoot' => string 'C:\WINDOWS' (length=10) 'COMSPEC' => string 'C:\WINDOWS\system32\cmd.exe' (length=27) 'PATHEXT' => string '.COM;.EXE;.BAT;.CMD;.VBS;.VBE;.JS;.JSE;.WSF;.WSH;.MSC' (length=53) 'WINDIR' => string 'C:\WINDOWS' (length=10) 'SERVER_SIGNATURE' => string '' (length=0) 'SERVER_SOFTWARE' => string 'Apache/2.4.18 (Win64) OpenSSL/1.0.2g PHP/5.6.19' (length=47) 'SERVER_NAME' => string 'localhost' (length=9) 'SERVER_ADDR' => string '::1' (length=3) 'SERVER_PORT' => string '80' (length=2) 'REMOTE_ADDR' => string '::1' (length=3) 'DOCUMENT_ROOT' => string 'D:/wampserver/www' (length=17) 'REQUEST_SCHEME' => string 'http' (length=4) 'CONTEXT_PREFIX' => string '' (length=0) 'CONTEXT_DOCUMENT_ROOT' => string 'D:/wampserver/www' (length=17) 'SERVER_ADMIN' => string 'admin@example.com' (length=17) 'SCRIPT_FILENAME' => string 'D:/wampserver/www/test/$_SERVER.php' (length=35) 'REMOTE_PORT' => string '57305' (length=5) 'GATEWAY_INTERFACE' => string 'CGI/1.1' (length=7) 'SERVER_PROTOCOL' => string 'HTTP/1.1' (length=8) 'REQUEST_METHOD' => string 'GET' (length=3) 'QUERY_STRING' => string '' (length=0) 'REQUEST_URI' => string '/test/$_SERVER.php' (length=18) 'SCRIPT_NAME' => string '/test/$_SERVER.php' (length=18) 'PHP_SELF' => string '/test/$_SERVER.php' (length=18) 'REQUEST_TIME_FLOAT' => float 1510122616.201 'REQUEST_TIME' => int 1510122616

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