";  /*    ./  表示当前文件所在的目录    ../ 表示当前文件所在目录的上一级目录  */  include ("./includedfile.php");  echo "
";  echo "绝对路径加载,__DIR__，方法一
";  include(__DIR__."/includedfile.php");  echo "
";  echo "绝对路径加载，\$_server['DOCUMENT_ROOT'],方法二
";  echo "根目录:".$_SERVER['DOCUMENT_ROOT']."
";  include($_SERVER['DOCUMENT_ROOT']."/includedfile.php"); ?>

 $_SERVER：