获取IP地址的代码

function ip() {
if (getenv ( 'HTTP_CLIENT_IP' ) && strcasecmp ( getenv ( 'HTTP_CLIENT_IP' ), 'unknown' )) {
$ip = getenv ( 'HTTP_CLIENT_IP' );
} elseif (getenv ( 'HTTP_X_FORWARDED_FOR' ) && strcasecmp ( getenv ( 'HTTP_X_FORWARDED_FOR' ), 'unknown' )) {
$ip = getenv ( 'HTTP_X_FORWARDED_FOR' );
} elseif (getenv ( 'REMOTE_ADDR' ) && strcasecmp ( getenv ( 'REMOTE_ADDR' ), 'unknown' )) {
$ip = getenv ( 'REMOTE_ADDR' );
} elseif (isset ( $_SERVER ['REMOTE_ADDR'] ) && $_SERVER ['REMOTE_ADDR'] && strcasecmp ( $_SERVER ['REMOTE_ADDR'], 'unknown' )) {
$ip = $_SERVER ['REMOTE_ADDR'];
}
return preg_match ( '/[\d\.]{7,15}/', $ip, $matches ) ? $matches [0] : '';
}
}