perl正则中后缀修饰符 /s和/m有什么区别？

justlooks

/s使.能够匹配\n ,那么可以跨行匹配文本，/m呢？

zzy7186

m 是将字符串作为多行处理，s是将字符串作为单行处理，如果是s在字符串中出现的\n就相当于普通字符。

justlooks

回复 2# zzy7186


理解了

zhlong8

perldoc perlre 第一小节讲了所有修饰符 "msgixcp"

Perl_Er

回复 1# justlooks


   

6.6. Matching Within Multiple Lines
6.6.1. Problem
You want to use regular expressions on a string containing more than one logical line, but the special characters . (any character but newline), ^ (start of string), and $ (end of string) don't seem to work for you. This might happen if you're reading in multiline records or the whole file at once.

6.6.2. Solution
Use /m, /s, or both as pattern modifiers. /s allows . to match a newline (normally it doesn't). If the target string has more than one line in it, /foo.*bar/s could match a "foo" on one line and a "bar" on a following line. This doesn't affect dots in character classes like [#%.], since they are literal periods anyway.

The /m modifier allows ^ and $ to match immediately before and after an embedded newline, respectively. /^=head[1-7]/m would match that pattern not just at the beginning of the record, but anywhere right after a newline as well.

justlooks

对的