PHP学习之预定义变量(实例讲解)

超全局变量

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。

<?phpfunction test() {  $foo = "local variable";  echo "$foo in global scope: " . $GLOBALS["foo"] . "";  echo "$foo in current scope: " . $foo . "";}$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

<?PHPecho "<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:Workpython2.7;D:Workpython2.7Scripts;C:ProgramDataOracleJavajavapath;C:WINDOWSsystem32;C:WINDOWS;C:WINDOWSSystem32Wbem;C:WINDOWSSystem32WindowsPowerShellv1.0;D:wampservermysqlin;D:WorkJAVA	omcatin;D:WorkMozilla Firefoxfirefox.exe;D:Workphantomjsin;D:Workchormedriver;C:WINDOWSsystem32configsystemprofile.dnxin;C:Program FilesMicrosoft DNXDnvm;C:Program FilesMicrosoft SQL Server130ToolsBinn;D:wampserverphp;C:ProgramDataComposerSetupi"... (length=607) "SystemRoot" => string "C:WINDOWS" (length=10) "COMSPEC" => string "C:WINDOWSsystem32cmd.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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