• perl 跨行匹配;


    <pre name="code" class="html"><pre name="code" class="html">perl  跨行匹配;
    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.
    
    
    多行匹配
    
    6.6.1 问题
    
    
    你需要使用正则表达式在一个自付出啊吧 包含多个逻辑行, 但是特定的字符串(任何字符串除了换行) 
    
    ^ 表示字符串开始
    
    $ 字符串结束 似乎不能为你工作 。
    
    这个可能发生如果你读取多行 记录 
    
    
    6.6.2 解决
    
    使用/m ,/s  或者两者  作为模式修改 
    
    /s 允许. 匹配一个换行(通常它不能)  如果目标字符串有多余一行,
    
    /foo,*bar/s  可以匹配一个"foo 在一行和一个"bar" 在另外一行  这个不会影响点号 在字符类 
    the "." metacharacter matches any character except
        "
    " (unless you use "/s")
    
    
    
    /m 修饰符 允许 ^和$来立即匹配 之前和之后一个嵌入的换行符,分别的,
    
    
    /^=head[1-7]/m
    
    会匹配 模式不是在记录的开始,但是任何右边在一个新行
    
    
    
    
    /s 当作一行处理
    
    /s 令 . 匹配换行符并且忽略不建议使用的 $* 变量
    
    /m 令 ^ 和 $ 匹配下一个嵌入的 
    。
    
    
    zjtest7-frontend:/root# cat a2.pl 
    my $str="sdgs
    sdgdsg
    begin
    ddd
    ...
    end 
    d,,,,
    sdsdg
    begin 
    sdsg
    end ";
    if ($str =~/.*?begin.(.*).end/s){
        print "$1 is $1
    ";
       };
       
    
    
    zjtest7-frontend:/root# perl a2.pl 
    $1 is ddd
    ...
    end 
    d,,,,
    sdsdg
    begin 
    sdsg
    
    
    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.
    


    
    
    
                                        
    
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  • 原文地址:https://www.cnblogs.com/hzcya1995/p/13350411.html
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