正则表达式模式，可匹配没有任何2个连续重复字符的字符串 [英] Regular expression pattern to match string without any 2 consecutive repeated characters

问题描述

我可以很容易地编写一个正则表达式来匹配包含2个连续重复字符的字符串:

I can very easily write a regular expression to match a string that contains 2 consecutive repeated characters:

/(\w)\1/

我该如何做呢?我想匹配没有2个连续重复字符的字符串.我尝试了以下各种变体，但均未成功:

How do I do the complement of that? I want to match strings that don't have 2 consecutive repeated characters. I've tried variations of the following without success:

/(\w)[^\1]/ ;doesn't work as hoped
/(?!(\w)\1)/ ;looks ahead, but some portion of the string will match
/(\w)(?!\1)/ ;again, some portion of the string will match

我不希望使用任何特定于语言/平台的方式来取反正则表达式.我想要一种简单的方法.

I don't want any language/platform specific way to take the negation of a regular expression. I want the straightforward way to do this.

推荐答案

下面的正则表达式将匹配没有重复字符的字符串.

The below regex would match the strings which don't have any repeated characters.

^(?!.*(\w)\1).*

(?!.*(\w)\1)否定前瞻，它断言要匹配的字符串将不包含任何重复的字符. .*(\w)\1将匹配在中间或开头或结尾重复字符的字符串. ^(?!.*(\w)\1)匹配除具有重复字符的边界以外的所有起始边界.并且以下.*匹配该特定行上存在的所有字符.请注意，这也匹配空字符串.如果您不想匹配空行，请最后将.*更改为.+

(?!.*(\w)\1) negative lookahead which asserts that the string going to be matched won't contain any repeated characters. .*(\w)\1 will match the string which has repeated characters at the middle or at the start or at the end. ^(?!.*(\w)\1) matches all the starting boundaries except the one which has repeated characters. And the following .* matches all the characters exists on that particular line. Note this this matches empty strings also. If you don't want to match empty lines then change .* at the last to .+

请注意，^(?!(\w)\1)仅在字符串或行的开头检查重复的字符.

Note that ^(?!(\w)\1) checks for the repeated characters only at the start of a string or line.

前瞻性和后视性统称为环顾四周" ，它们都是零长度的断言就像行的开始和结束一样.它们不使用字符串中的字符，而仅声明是否可以匹配.环顾四周功能可让您创建没有正则表达式就无法创建的正则表达式，或者如果没有正则表达式会非常冗长.

Lookahead and lookbehind, collectively called "lookaround", are zero-length assertions just like the start and end of line. They do not consume characters in the string, but only assert whether a match is possible or not. Lookaround allows you to create regular expressions that are impossible to create without them, or that would get very longwinded without them.

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