PHP method for server-side predefined variable $_SERVER

This article mainly introduces PHP's method for server-side predefined variables $_SERVER. Interested friends can refer to it. I hope it will be helpful to everyone.

The example of this article describes how PHP determines the access IP, as follows:

<?php 
function getIP() { 
  if (! empty ( $_SERVER ["HTTP_CLIENT_IP"] )) { 
    $cip = $_SERVER ["HTTP_CLIENT_IP"]; 
  } else if (! empty ( $_SERVER ["HTTP_X_FORWARDED_FOR"] )) { 
    $cip = $_SERVER ["HTTP_X_FORWARDED_FOR"]; 
  } else if (! empty ( $_SERVER ["REMOTE_ADDR"] )) { 
    $cip = $_SERVER ["REMOTE_ADDR"]; 
  } else { 
    $cip = &#39;&#39;; 
  } 
  preg_match ( "/[\d\.]{7,15}/", $cip, $cips ); 
  $cip = isset ( $cips [0] ) ? $cips [0] : &#39;unknown&#39;; 
  unset ( $cips ); 
  return $cip; 
} 
?>

Summary: The above is the entire content of this article, I hope it will be helpful to everyone's study .

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