正则表达式的详细规则和实例

短命女 2022-09-23 12:47 187阅读 0赞

## 正则表达式速查表 ##

<table style="background-color:rgb(249,249,249); border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); border-collapse:collapse; color:black; font-family:Verdana,Geneva,sans-serif"> 
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 <th style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); padding-top:4px; padding-right:4px; padding-bottom:4px; padding-left:4px; font-weight:normal; background-color:rgb(219,229,241); text-align:center; font-size:18px"> 字符</th> 
 <th style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); padding-top:4px; padding-right:4px; padding-bottom:4px; padding-left:4px; font-weight:normal; background-color:rgb(219,229,241); text-align:center; font-size:18px"> 描述</th> 
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 <th style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); padding-top:4px; padding-right:4px; padding-bottom:4px; padding-left:4px; font-weight:normal; background-color:rgb(219,229,241); text-align:center"> \</th> 
 <td style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); line-height:20px; padding-top:5px; padding-right:8px; padding-bottom:5px; padding-left:8px"> 将下一个字符标记为一个特殊字符、或一个原义字符、或一个向后引用、或一个八进制转义符。例如，“<code>n</code>”匹配字符“<code>n</code>”。“<code>\n</code>”匹配一个换行符。串行“<code>\\</code>”匹配“<code>\</code>”而“<code>\(</code>”则匹配“<code>(</code>”。</td> 
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 <th style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); padding-top:4px; padding-right:4px; padding-bottom:4px; padding-left:4px; font-weight:normal; background-color:rgb(219,229,241); text-align:center"> ^</th> 
 <td style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); line-height:20px; padding-top:5px; padding-right:8px; padding-bottom:5px; padding-left:8px"> 匹配输入字符串的开始位置。如果设置了RegExp对象的Multiline属性，^也匹配“<code>\n</code>”或“<code>\r</code>”之后的位置。</td> 
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 <th style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); padding-top:4px; padding-right:4px; padding-bottom:4px; padding-left:4px; font-weight:normal; background-color:rgb(219,229,241); text-align:center"> $</th> 
 <td style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); line-height:20px; padding-top:5px; padding-right:8px; padding-bottom:5px; padding-left:8px"> 匹配输入字符串的结束位置。如果设置了RegExp对象的Multiline属性，$也匹配“<code>\n</code>”或“<code>\r</code>”之前的位置。</td> 
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 <th style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); padding-top:4px; padding-right:4px; padding-bottom:4px; padding-left:4px; font-weight:normal; background-color:rgb(219,229,241); text-align:center"> *</th> 
 <td style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); line-height:20px; padding-top:5px; padding-right:8px; padding-bottom:5px; padding-left:8px"> 匹配前面的子表达式零次或多次。例如，zo*能匹配“<code>z</code>”以及“<code>zoo</code>”。*等价于{0,}。</td> 
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 <th style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); padding-top:4px; padding-right:4px; padding-bottom:4px; padding-left:4px; font-weight:normal; background-color:rgb(219,229,241); text-align:center"> +</th> 
 <td style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); line-height:20px; padding-top:5px; padding-right:8px; padding-bottom:5px; padding-left:8px"> 匹配前面的子表达式一次或多次。例如，“<code>zo+</code>”能匹配“<code>zo</code>”以及“<code>zoo</code>”，但不能匹配“<code>z</code>”。+等价于{1,}。</td> 
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 <th style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); padding-top:4px; padding-right:4px; padding-bottom:4px; padding-left:4px; font-weight:normal; background-color:rgb(219,229,241); text-align:center"> ?</th> 
 <td style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); line-height:20px; padding-top:5px; padding-right:8px; padding-bottom:5px; padding-left:8px"> 匹配前面的子表达式零次或一次。例如，“<code>do(es)?</code>”可以匹配“<code>does</code>”或“<code>does</code>”中的“<code>do</code>”。?等价于{0,1}。</td> 
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 <th style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); padding-top:4px; padding-right:4px; padding-bottom:4px; padding-left:4px; font-weight:normal; background-color:rgb(219,229,241); text-align:center"> { n}</th> 
 <td style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); line-height:20px; padding-top:5px; padding-right:8px; padding-bottom:5px; padding-left:8px"> n是一个非负整数。匹配确定的n次。例如，“<code>o{2}</code>”不能匹配“<code>Bob</code>”中的“<code>o</code>”，但是能匹配“<code>food</code>”中的两个o。</td> 
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 <th style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); padding-top:4px; padding-right:4px; padding-bottom:4px; padding-left:4px; font-weight:normal; background-color:rgb(219,229,241); text-align:center"> { n,}</th> 
 <td style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); line-height:20px; padding-top:5px; padding-right:8px; padding-bottom:5px; padding-left:8px"> n是一个非负整数。至少匹配n次。例如，“<code>o{2,}</code>”不能匹配“<code>Bob</code>”中的“<code>o</code>”，但能匹配“<code>foooood</code>”中的所有o。“<code>o{1,}</code>”等价于“<code>o+</code>”。“<code>o{0,}</code>”则等价于“<code>o*</code>”。</td> 
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 <th style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); padding-top:4px; padding-right:4px; padding-bottom:4px; padding-left:4px; font-weight:normal; background-color:rgb(219,229,241); text-align:center"> { n,m}</th> 
 <td style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); line-height:20px; padding-top:5px; padding-right:8px; padding-bottom:5px; padding-left:8px"> m和n均为非负整数，其中n&lt;=m。最少匹配n次且最多匹配m次。例如，“<code>o{1,3}</code>”将匹配“<code>fooooood</code>”中的前三个o。“<code>o{0,1}</code>”等价于“<code>o?</code>”。请注意在逗号和两个数之间不能有空格。</td> 
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 <th style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); padding-top:4px; padding-right:4px; padding-bottom:4px; padding-left:4px; font-weight:normal; background-color:rgb(219,229,241); text-align:center"> ?</th> 
 <td style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); line-height:20px; padding-top:5px; padding-right:8px; padding-bottom:5px; padding-left:8px"> 当该字符紧跟在任何一个其他限制符（*,+,?，{ n}，{ n,}，{ n,m}）后面时，匹配模式是非贪婪的。非贪婪模式尽可能少的匹配所搜索的字符串，而默认的贪婪模式则尽可能多的匹配所搜索的字符串。例如，对于字符串“<code>oooo</code>”，“<code>o+?</code>”将匹配单个“<code>o</code>”，而“<code>o+</code>”将匹配所有“<code>o</code>”。</td> 
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 <th style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); padding-top:4px; padding-right:4px; padding-bottom:4px; padding-left:4px; font-weight:normal; background-color:rgb(219,229,241); text-align:center"> .</th> 
 <td style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); line-height:20px; padding-top:5px; padding-right:8px; padding-bottom:5px; padding-left:8px"> 匹配除“<code>\</code><code>n</code>”之外的任何单个字符。要匹配包括“<code>\</code><code>n</code>”在内的任何字符，请使用像“<code>(.|\n)</code>”的模式。</td> 
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 <th style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); padding-top:4px; padding-right:4px; padding-bottom:4px; padding-left:4px; font-weight:normal; background-color:rgb(219,229,241); text-align:center"> (pattern)</th> 
 <td style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); line-height:20px; padding-top:5px; padding-right:8px; padding-bottom:5px; padding-left:8px"> 匹配pattern并获取这一匹配。所获取的匹配可以从产生的Matches集合得到，在VBScript中使用SubMatches集合，在JScript中则使用$0…$9属性。要匹配圆括号字符，请使用“<code>$</code>”或“<code>$</code>”。</td> 
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 <th style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); padding-top:4px; padding-right:4px; padding-bottom:4px; padding-left:4px; font-weight:normal; background-color:rgb(219,229,241); text-align:center"> (?:pattern)</th> 
 <td style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); line-height:20px; padding-top:5px; padding-right:8px; padding-bottom:5px; padding-left:8px"> 匹配pattern但不获取匹配结果，也就是说这是一个非获取匹配，不进行存储供以后使用。这在使用或字符“<code>(|)</code>”来组合一个模式的各个部分是很有用。例如“<code>industr(?:y|ies)</code>”就是一个比“<code>industry|industries</code>”更简略的表达式。</td> 
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 <th style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); padding-top:4px; padding-right:4px; padding-bottom:4px; padding-left:4px; font-weight:normal; background-color:rgb(219,229,241); text-align:center"> (?=pattern)</th> 
 <td style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); line-height:20px; padding-top:5px; padding-right:8px; padding-bottom:5px; padding-left:8px"> 正向肯定预查，在任何匹配pattern的字符串开始处匹配查找字符串。这是一个非获取匹配，也就是说，该匹配不需要获取供以后使用。例如，“<code>Windows(?=95|98|NT|2000)</code>”能匹配“<code>Windows2000</code>”中的“<code>Windows</code>”，但不能匹配“<code>Windows3.1</code>”中的“<code>Windows</code>”。预查不消耗字符，也就是说，在一个匹配发生后，在最后一次匹配之后立即开始下一次匹配的搜索，而不是从包含预查的字符之后开始。</td> 
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 <th style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); padding-top:4px; padding-right:4px; padding-bottom:4px; padding-left:4px; font-weight:normal; background-color:rgb(219,229,241); text-align:center"> (?!pattern)</th> 
 <td style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); line-height:20px; padding-top:5px; padding-right:8px; padding-bottom:5px; padding-left:8px"> 正向否定预查，在任何不匹配pattern的字符串开始处匹配查找字符串。这是一个非获取匹配，也就是说，该匹配不需要获取供以后使用。例如“<code>Windows(?!95|98|NT|2000)</code>”能匹配“<code>Windows3.1</code>”中的“<code>Windows</code>”，但不能匹配“<code>Windows2000</code>”中的“<code>Windows</code>”。预查不消耗字符，也就是说，在一个匹配发生后，在最后一次匹配之后立即开始下一次匹配的搜索，而不是从包含预查的字符之后开始</td> 
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 <th style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); padding-top:4px; padding-right:4px; padding-bottom:4px; padding-left:4px; font-weight:normal; background-color:rgb(219,229,241); text-align:center"> (?&lt;=pattern)</th> 
 <td style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); line-height:20px; padding-top:5px; padding-right:8px; padding-bottom:5px; padding-left:8px"> 反向肯定预查，与正向肯定预查类拟，只是方向相反。例如，“<code>(?&lt;=95|98|NT|2000)Windows</code>”能匹配“<code>2000Windows</code>”中的“<code>Windows</code>”，但不能匹配“<code>3.1Windows</code>”中的“<code>Windows</code>”。</td> 
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 <th style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); padding-top:4px; padding-right:4px; padding-bottom:4px; padding-left:4px; font-weight:normal; background-color:rgb(219,229,241); text-align:center"> (?&lt;!pattern)</th> 
 <td style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); line-height:20px; padding-top:5px; padding-right:8px; padding-bottom:5px; padding-left:8px"> 反向否定预查，与正向否定预查类拟，只是方向相反。例如“<code>(?&lt;!95|98|NT|2000)Windows</code>”能匹配“<code>3.1Windows</code>”中的“<code>Windows</code>”，但不能匹配“<code>2000Windows</code>”中的“<code>Windows</code>”。</td> 
 </tr> 
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 <th style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); padding-top:4px; padding-right:4px; padding-bottom:4px; padding-left:4px; font-weight:normal; background-color:rgb(219,229,241); text-align:center"> x|y</th> 
 <td style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); line-height:20px; padding-top:5px; padding-right:8px; padding-bottom:5px; padding-left:8px"> 匹配x或y。例如，“<code>z|food</code>”能匹配“<code>z</code>”或“<code>food</code>”。“<code>(z|f)ood</code>”则匹配“<code>zood</code>”或“<code>food</code>”。</td> 
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 <th style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); padding-top:4px; padding-right:4px; padding-bottom:4px; padding-left:4px; font-weight:normal; background-color:rgb(219,229,241); text-align:center"> [xyz]</th> 
 <td style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); line-height:20px; padding-top:5px; padding-right:8px; padding-bottom:5px; padding-left:8px"> 字符集合。匹配所包含的任意一个字符。例如，“<code>[abc]</code>”可以匹配“<code>plain</code>”中的“<code>a</code>”。</td> 
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 <th style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); padding-top:4px; padding-right:4px; padding-bottom:4px; padding-left:4px; font-weight:normal; background-color:rgb(219,229,241); text-align:center"> [^xyz]</th> 
 <td style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); line-height:20px; padding-top:5px; padding-right:8px; padding-bottom:5px; padding-left:8px"> 负值字符集合。匹配未包含的任意字符。例如，“<code>[^abc]</code>”可以匹配“<code>plain</code>”中的“<code>p</code>”。</td> 
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 <th style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); padding-top:4px; padding-right:4px; padding-bottom:4px; padding-left:4px; font-weight:normal; background-color:rgb(219,229,241); text-align:center"> [a-z]</th> 
 <td style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); line-height:20px; padding-top:5px; padding-right:8px; padding-bottom:5px; padding-left:8px"> 字符范围。匹配指定范围内的任意字符。例如，“<code>[a-z]</code>”可以匹配“<code>a</code>”到“<code>z</code>”范围内的任意小写字母字符。</td> 
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 <th style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); padding-top:4px; padding-right:4px; padding-bottom:4px; padding-left:4px; font-weight:normal; background-color:rgb(219,229,241); text-align:center"> [^a-z]</th> 
 <td style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); line-height:20px; padding-top:5px; padding-right:8px; padding-bottom:5px; padding-left:8px"> 负值字符范围。匹配任何不在指定范围内的任意字符。例如，“<code>[^a-z]</code>”可以匹配任何不在“<code>a</code>”到“<code>z</code>”范围内的任意字符。</td> 
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 <th style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); padding-top:4px; padding-right:4px; padding-bottom:4px; padding-left:4px; font-weight:normal; background-color:rgb(219,229,241); text-align:center"> \b</th> 
 <td style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); line-height:20px; padding-top:5px; padding-right:8px; padding-bottom:5px; padding-left:8px"> 匹配一个单词边界，也就是指单词和空格间的位置。例如，“<code>er\b</code>”可以匹配“<code>never</code>”中的“<code>er</code>”，但不能匹配“<code>verb</code>”中的“<code>er</code>”。</td> 
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 <th style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); padding-top:4px; padding-right:4px; padding-bottom:4px; padding-left:4px; font-weight:normal; background-color:rgb(219,229,241); text-align:center"> \B</th> 
 <td style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); line-height:20px; padding-top:5px; padding-right:8px; padding-bottom:5px; padding-left:8px"> 匹配非单词边界。“<code>er\B</code>”能匹配“<code>verb</code>”中的“<code>er</code>”，但不能匹配“<code>never</code>”中的“<code>er</code>”。</td> 
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 <th style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); padding-top:4px; padding-right:4px; padding-bottom:4px; padding-left:4px; font-weight:normal; background-color:rgb(219,229,241); text-align:center"> \cx</th> 
 <td style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); line-height:20px; padding-top:5px; padding-right:8px; padding-bottom:5px; padding-left:8px"> 匹配由x指明的控制字符。例如，\cM匹配一个Control-M或回车符。x的值必须为A-Z或a-z之一。否则，将c视为一个原义的“<code>c</code>”字符。</td> 
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 <th style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); padding-top:4px; padding-right:4px; padding-bottom:4px; padding-left:4px; font-weight:normal; background-color:rgb(219,229,241); text-align:center"> \d</th> 
 <td style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); line-height:20px; padding-top:5px; padding-right:8px; padding-bottom:5px; padding-left:8px"> 匹配一个数字字符。等价于[0-9]。</td> 
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 <tr> 
 <th style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); padding-top:4px; padding-right:4px; padding-bottom:4px; padding-left:4px; font-weight:normal; background-color:rgb(219,229,241); text-align:center"> \D</th> 
 <td style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); line-height:20px; padding-top:5px; padding-right:8px; padding-bottom:5px; padding-left:8px"> 匹配一个非数字字符。等价于[^0-9]。</td> 
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 <tr> 
 <th style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); padding-top:4px; padding-right:4px; padding-bottom:4px; padding-left:4px; font-weight:normal; background-color:rgb(219,229,241); text-align:center"> \f</th> 
 <td style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); line-height:20px; padding-top:5px; padding-right:8px; padding-bottom:5px; padding-left:8px"> 匹配一个换页符。等价于\x0c和\cL。</td> 
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 <tr> 
 <th style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); padding-top:4px; padding-right:4px; padding-bottom:4px; padding-left:4px; font-weight:normal; background-color:rgb(219,229,241); text-align:center"> \n</th> 
 <td style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); line-height:20px; padding-top:5px; padding-right:8px; padding-bottom:5px; padding-left:8px"> 匹配一个换行符。等价于\x0a和\cJ。</td> 
 </tr> 
 <tr> 
 <th style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); padding-top:4px; padding-right:4px; padding-bottom:4px; padding-left:4px; font-weight:normal; background-color:rgb(219,229,241); text-align:center"> \r</th> 
 <td style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); line-height:20px; padding-top:5px; padding-right:8px; padding-bottom:5px; padding-left:8px"> 匹配一个回车符。等价于\x0d和\cM。</td> 
 </tr> 
 <tr> 
 <th style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); padding-top:4px; padding-right:4px; padding-bottom:4px; padding-left:4px; font-weight:normal; background-color:rgb(219,229,241); text-align:center"> \s</th> 
 <td style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); line-height:20px; padding-top:5px; padding-right:8px; padding-bottom:5px; padding-left:8px"> 匹配任何空白字符，包括空格、制表符、换页符等等。等价于[ \f\n\r\t\v]。</td> 
 </tr> 
 <tr> 
 <th style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); padding-top:4px; padding-right:4px; padding-bottom:4px; padding-left:4px; font-weight:normal; background-color:rgb(219,229,241); text-align:center"> \S</th> 
 <td style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); line-height:20px; padding-top:5px; padding-right:8px; padding-bottom:5px; padding-left:8px"> 匹配任何非空白字符。等价于[^ \f\n\r\t\v]。</td> 
 </tr> 
 <tr> 
 <th style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); padding-top:4px; padding-right:4px; padding-bottom:4px; padding-left:4px; font-weight:normal; background-color:rgb(219,229,241); text-align:center"> \t</th> 
 <td style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); line-height:20px; padding-top:5px; padding-right:8px; padding-bottom:5px; padding-left:8px"> 匹配一个制表符。等价于\x09和\cI。</td> 
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 <tr> 
 <th style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); padding-top:4px; padding-right:4px; padding-bottom:4px; padding-left:4px; font-weight:normal; background-color:rgb(219,229,241); text-align:center"> \v</th> 
 <td style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); line-height:20px; padding-top:5px; padding-right:8px; padding-bottom:5px; padding-left:8px"> 匹配一个垂直制表符。等价于\x0b和\cK。</td> 
 </tr> 
 <tr> 
 <th style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); padding-top:4px; padding-right:4px; padding-bottom:4px; padding-left:4px; font-weight:normal; background-color:rgb(219,229,241); text-align:center"> \w</th> 
 <td style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); line-height:20px; padding-top:5px; padding-right:8px; padding-bottom:5px; padding-left:8px"> 匹配包括下划线的任何单词字符。等价于“<code>[A-Za-z0-9_]</code>”。</td> 
 </tr> 
 <tr> 
 <th style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); padding-top:4px; padding-right:4px; padding-bottom:4px; padding-left:4px; font-weight:normal; background-color:rgb(219,229,241); text-align:center"> \W</th> 
 <td style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); line-height:20px; padding-top:5px; padding-right:8px; padding-bottom:5px; padding-left:8px"> 匹配任何非单词字符。等价于“<code>[^A-Za-z0-9_]</code>”。</td> 
 </tr> 
 <tr> 
 <th style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); padding-top:4px; padding-right:4px; padding-bottom:4px; padding-left:4px; font-weight:normal; background-color:rgb(219,229,241); text-align:center"> \xn</th> 
 <td style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); line-height:20px; padding-top:5px; padding-right:8px; padding-bottom:5px; padding-left:8px"> 匹配n，其中n为十六进制转义值。十六进制转义值必须为确定的两个数字长。例如，“<code>\x41</code>”匹配“<code>A</code>”。“<code>\x041</code>”则等价于“<code>\x04&amp;1</code>”。正则表达式中可以使用ASCII编码。.</td> 
 </tr> 
 <tr> 
 <th style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); padding-top:4px; padding-right:4px; padding-bottom:4px; padding-left:4px; font-weight:normal; background-color:rgb(219,229,241); text-align:center"> \num</th> 
 <td style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); line-height:20px; padding-top:5px; padding-right:8px; padding-bottom:5px; padding-left:8px"> 匹配num，其中num是一个正整数。对所获取的匹配的引用。例如，“<code>(.)\1</code>”匹配两个连续的相同字符。</td> 
 </tr> 
 <tr> 
 <th style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); padding-top:4px; padding-right:4px; padding-bottom:4px; padding-left:4px; font-weight:normal; background-color:rgb(219,229,241); text-align:center"> \n</th> 
 <td style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); line-height:20px; padding-top:5px; padding-right:8px; padding-bottom:5px; padding-left:8px"> 标识一个八进制转义值或一个向后引用。如果\n之前至少n个获取的子表达式，则n为向后引用。否则，如果n为八进制数字（0-7），则n为一个八进制转义值。</td> 
 </tr> 
 <tr> 
 <th style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); padding-top:4px; padding-right:4px; padding-bottom:4px; padding-left:4px; font-weight:normal; background-color:rgb(219,229,241); text-align:center"> \nm</th> 
 <td style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); line-height:20px; padding-top:5px; padding-right:8px; padding-bottom:5px; padding-left:8px"> 标识一个八进制转义值或一个向后引用。如果\nm之前至少有nm个获得子表达式，则nm为向后引用。如果\nm之前至少有n个获取，则n为一个后跟文字m的向后引用。如果前面的条件都不满足，若n和m均为八进制数字（0-7），则\nm将匹配八进制转义值nm。</td> 
 </tr> 
 <tr> 
 <th style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); padding-top:4px; padding-right:4px; padding-bottom:4px; padding-left:4px; font-weight:normal; background-color:rgb(219,229,241); text-align:center"> \nml</th> 
 <td style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); line-height:20px; padding-top:5px; padding-right:8px; padding-bottom:5px; padding-left:8px"> 如果n为八进制数字（0-3），且m和l均为八进制数字（0-7），则匹配八进制转义值nml。</td> 
 </tr> 
 <tr> 
 <th style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); padding-top:4px; padding-right:4px; padding-bottom:4px; padding-left:4px; font-weight:normal; background-color:rgb(219,229,241); text-align:center"> \un</th> 
 <td style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(150,178,211); border-right-color:rgb(150,178,211); border-bottom-color:rgb(150,178,211); border-left-color:rgb(150,178,211); line-height:20px; padding-top:5px; padding-right:8px; padding-bottom:5px; padding-left:8px"> 匹配n，其中n是一个用四个十六进制数字表示的Unicode字符。例如，\u00A9匹配版权符号（©）。</td> 
 </tr> 
 </tbody> 
</table>

## 常用正则表达式 ##