php能替换html的文本内容吗

$a="<p><img src=\"/upload/store/1/ue/image/1568282125833264.png\" title=\"1568282125833264.png\" alt=\"1.png\"/><img src=\"http://dimg04.c-ctrip.com/images/300q12000000rq2t956CB.jpg\" alt=\"undefined\"/><img  src=\"https://dimg04.c-ctrip.com/images/300m12000000sdsca92E2.jpg\"/ alt="php能替换html的文本内容吗" ><img src=\"https://dimg04.c-ctrip.com/images/300w12000000rutmrD6CB.jpg\" alt=\"undefined\"/><img src=\"https://dimg04.c-ctrip.com/images/300u12000000rorex415F.jpg\" alt=\"undefined\"/><img src=\"http://dimg04.c-ctrip.com/images/300k12000000rsyxgBA05.jpg\" alt=\"undefined\"/></p>"

$pattern="/<img .*?src=[\&#39;|\"](.*?)[\&#39;|\"].*?[\/]? alt="php能替换html的文本内容吗" >/";
preg_match_all($pattern,htmlspecialchars_decode($a),$match);
if(!empty($match[1])){
    print_r($match[1]);
}else{
echo "没得";
}

$host="http://mp.csdn.net"
$newContent =  preg_replace_callback("/<img .*?src=[\&#39;|\"](.*?)[\&#39;|\"].*?[\/]? alt="php能替换html的文本内容吗" >/", function($m) use($host){

   if(strpos($m[1],&#39;http://&#39;) || strpos($m[1],&#39;https://&#39;)){
       return $m[0];
   }else{
       $img=preg_replace(&#39;#src="/#is&#39;, &#39;src="&#39;.$host.&#39;/&#39;,$m[0]);
       return $img;
   }
}, $a);