正则，如果img标签里没有alt，则加上alt=""
正则，如果img标签里没有alt，则加上alt= " "

<img src= "asdfas.gif " width= " " heigth= " " alt= "dsafa ">
-->
<img src= "asdfas.gif " width= " " heigth= " " alt= "dsafa ">

<img src= "asdfas.gif " width= " " heigth= " ">
-->
<img src= "asdfas.gif " width= " " heigth= " " alt= "dsafa ">

意思就是，有的话不管，没有则加上一个


[解决办法]
DC关注
[解决办法]
( <img(?![^\x3E]*?alt[^\x3E]*?> ).*?)>
可以吗？
[解决办法]
jf