PHP查询显示关键字为红色

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一段很简单的代码，刚刚写的时候有用，平时是用来替换空格为-的 <?PHP $rep_product_id=$myrow["product_id"];           if (substr_count($rep_product_id,"$keywords")>0){                 $rep_product_id= str_replace("$keywords","<font color=red>".$keywords."</font>",$rep_product_id);                 }                 echo $rep_product_id?> PHP查询显示关键字为红色