PHP的等于判断

各位看看应该输出什么

<?php
$curMac = &#39;00E031001774&#39;;
$preMac = &#39;00E012013732&#39;;
if($curMac != $preMac){
    echo &#39;not not&#39;;
}else{
    echo &#39;yes yes&#39;;
}
?>