<img class="emoji" title="" src="https://xxx.com/data/57@2x.png">我<img class="emoji" title="" src="https://xxx.com/data/57@2x.png">
类似这种 匹配到<img class="emoji" title="" src="https://xxx.com/data/57@2x.png"> 将他替换成对应的内容
demo
$str = '<img class="emoji" title="" src="https://xxx.com/data/1@2x.png">我<img class="emoji" title="" src="https://xxx.com/data/2@2x.png">他';
$p = '/<img class="emoji" title="" src="https:\/\/xxx\.com\/data\/(\d+)@2x\.png">/';
$str = preg_replace($p, 'm00$1', $str);
echo $str;如有帮助请采纳 谢谢
<img class="emoji" title="" src="https://xxx.com/data/1@2x.png">我<img class="emoji" title="" src="https://xxx.com/data/2@2x.png">他
<img class="emoji" title="" src="https://xxx.com/data/1@2x.png"> 对应的编码 m001
<img class="emoji" title="" src="https://xxx.com/data/2@2x.png"> 对应的编码 m002
最终的结果 m001我m002他