


Detailed explanation of the steps to use \B and \b in regular expressions
这次给大家带来正则表达式中的\B和\b使用步骤详解,正则表达式中的\B和\b的注意事项有哪些,下面就是实战案例,一起来看一下。
或许你看了下面这篇博客 你就能够对\B和\b认识加深了
根据查看API可以知道 \B和\b都是边界匹配符
先说说\b这个单词边界吧!竟然想了解 首先必须清楚什么叫单词边界!我们可以以\b为分割来探究一下
单词边界
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运行结果
分割的字符串:[(]
分割的字符串:[中文问号]
分割的字符串:[?]
分割的字符串:[123]
分割的字符串:[???]
分割的字符串:[英文]
分割的字符串:[)]
分割的字符串:[问号]
分割的字符串:[?]
分割的字符串:[我是华丽]
分割的字符串:[[]
分割的字符串:[的制表符]
分割的字符串:[ ]]
分割的字符串:[我是华丽]
分割的字符串:[{]
分割的字符串:[的空格符]
分割的字符串:[ ]
分割的字符串:[我是华丽]
分割的字符串:[}]
分割的字符串:[的换行符]
分割的字符串:[
]
从这些分割的字符串中我们可以知道单词边界就是单词和符号之间的边界
这里的单词可以是中文字符,英文字符,数字;符号可以是中文符号,英文符号,空格,制表符,换行
下面我们看一个例子
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在没有看上面分割的例子前估计很多人包括我都会认为这运行的结果是匹配成功
经过分割的例子后就知道了 空格并不是边界 空格与数字2之间的那个才叫边界 所以运行结果不言而喻 肯定是匹配不成功
当如果你这样写就运行出来就是匹配成功
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\b的用法
一般来说\b不用来判断当前字符串是否符合某种规则
一般我们都用\b来进行获取
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运行结果
呵呵1
\B的用法
了解了\b的用法 我们再来说说\B \B是非单词边界
也就说\B=[^\b]//符号^是非的意思1
\b是单词与符号的边界 那非单词与符号的边界的其它都是\B
所以我们的猜想\B是符号与符号,单词与单词的边界
当然猜想需要认证!下面我们写一个例子来证明一个!
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运行结果
分割的字符串:1
分割的字符串:2
分割的字符串:3
分割的字符串:4
分割的字符串:5
分割的字符串:6
分割的字符串:我
分割的字符串:是
分割的字符串:J
分割的字符串:A
分割的字符串:V
分割的字符串:A{ //单词与符号之间的边界不算\B的边界
分割的字符串:,
分割的字符串:、
分割的字符串:;
分割的字符串:‘a
分割的字符串:s
分割的字符串:d
事实证明\B作为非单词边界 确实是单词与单词,符号与符号之间的边界
\B一般也是用来获取字符串的
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因为字符与字符之间的边界
所以运行的结果是
呵
相信看了本文案例你已经掌握了方法,更多精彩请关注php中文网其它相关文章!
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