这个正则表如何理解？

[hackem]

/<img src="(.*?)"/m

===
我想应该是捕获网页的图片
<img src="
这样开始的行，但不明白后面的"(.*?)"/m

[ziyun]

你把表达式写完整看看

[eexpress]

带?结束的。

[csbde]

带?结束的，不然不会有个?

[5451vs5451]

代码： 全选

$ perldoc perlre
......
       By default, a quantified subpattern is "greedy", that is, it will match as many times as possible (given a partic‐
       ular starting location) while still allowing the rest of the pattern to match.  If you want it to match the mini‐
       mum number of times possible, follow the quantifier with a "?".  Note that the meanings don’t change, just the
       "greediness":

           *?     Match 0 or more times
           +?     Match 1 or more times
           ??     Match 0 or 1 time
           {n}?   Match exactly n times
           {n,}?  Match at least n times
           {n,m}? Match at least n but not more than m times
......

如果这是一个 perl 正则表达式，那么它相当于/<img src="([^"]*)"/m。后面的 m 指多行匹配，也就是允许 '.' 匹配 '\n'。