PHP learning: details of predefined variables

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
   
$_SERVER   
echo " 
"; 
var_dump($_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 'https://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