PHP正则如何匹配图片

Question

preg_match('#<img.+?src="[^>"]+?([^"/]+?)"[^>]+>#is', '<img src="http://127.0.0.1:81/upload/files/aaa.jpg" alt="大幅度4" >', $matches); 
echo $matches[0];这里匹配图片了， 但我想匹配图片里 alt="" 的图片 怎么匹配呢 

Answer 1

preg_match('/<img.+?src=["\'](.*?)["\'].*?alt=""/is', '<img src="http://127.0.0.1:81/upload/files/aaa.jpg" alt="" >', $matches); 
echo $matches[0];

Answer 2

alt="" 改成 alt="(.+?)"试试看看

Answer 3

不行哦 。 而且要求的是 获取 alt="" 的 图片

Answer 4

preg_match('/<img.+?src=["\'](.*?)["\'].*?alt=""/is', '<img src="http://127.0.0.1:81/upload/files/aaa.jpg" alt="" >', $matches); 
echo $matches[1];测试没问题

Answer 5

<?php
preg_match('#<img.+?src="[^>"]+?([^"/]+?)"[^>]*alt="([^"]*)"[^>]*>#is', '<img src="http://127.0.0.1:81/upload/files/aaa.jpg" alt="大幅度4" >', $matches); 
print_r($matches);