(PHP) 正規表現 - 大文字と小文字を区別しない

<?php
/**
 * Created by PhpStorm.
 * User: Ollydebug
 * Date: 2015/11/15
 * Time: 15:20
 */

/*
 * U-懒惰匹配
 * i-忽略英文字母大小写
 * x-忽略空白
 * s-让元字符&#39; . &#39;匹配包括换行符内所有字符
 */

$pattern = &#39;/GoOgle.+123/Ui&#39;;
$subject = &#39;I love google__123123123123123123&#39;;

$matches = array();
preg_match($pattern,$subject,$matches);

show($matches);

function show($var){
    if(empty($var)){
        echo &#39;null&#39;;
    }elseif(is_array($var)||is_object($var)){
        // array,object
        echo &#39;<pre class="brush:php;toolbar:false">&#39;;
        print_r($var);
        echo &#39;