.NET正EX pression其中检查长度和非字母数字字符 [英] .NET Regular expression which check length and non-alphanumeric characters

问题描述

我需要的正则表达式验证字符串具有最小长度为6，它是包含至少一个非字母数字字符，例如：EN％{S $ U），h9YI＆GT;！4J，{9YI;！4J，恩％ {S $ usdf），dfh9YI＆GT;！4J，ghffg {9YI;！4J。

这一个运作良好 ^ *（？= {6}）（？=。* \\ D）。* $但在情况下，当字符串中不包含任何数字（例如EN％{S $ U））这是行不通的。

解决方案

  ^（？=。{6}）（。* [^ 0-9A-ZA-Z]。* ）$
 

我们用积极的前瞻，以确保至少有6个字符。然后我们相匹配，看起来至少有一个非字母数字字符模式（ [^ 0-9A-ZA-Z] ）。该。* 的匹配任何数量的围绕这一非字母数字字符的任意字符，但我们已经检查过我们，我们在这里达成的时间匹配的至少6

  ^ *（？= {6}）（？=。* \\ D）。* $
 

是您尝试正则表达式。下面是一些建议：

• 您不需要在先行匹配超过6个字符。匹配这里只有6并没有经常EX pression其余从匹配600多限制。
• \ D 匹配一个数字，而（？=。* \\ D）是一个超前一对他们。这就是为什么你遇到你喜欢 EN％字符串提到的问题{S $ U）。
• 即使上面的观点是不是不正确的，在这里经常EX pression是正确的，你可以结合第二个先行与。* 下面由只使用。* \\Ð。* 。

I need Regexp to validate string has minimum length 6 and it is contains at least one non-alphanumeric character e.g: "eN%{S$u)", "h9YI!>4j", "{9YI!;4j", "eN%{S$usdf)", "dfh9YI!>4j", "ghffg{9YI!;4j".

This one is working well ^.*(?=.{6,})(?=.*\\d).*$" but in cases when string does not contain any numbers(e.g "eN%{S$u)") it is not working.

解决方案

^(?=.{6})(.*[^0-9a-zA-Z].*)$

We use positive lookahead to assure there are at least 6 characters. Then we match the pattern that looks for at least one non-alphanumeric character ([^0-9a-zA-Z]). The .*'s match any number of any characters around this one non-alphanumeric character, but by the time we've reached here we've already checked that we're matching at least 6.

^.*(?=.{6,})(?=.*\\d).*$"

is the regex you tried. Here are some suggestions:

• You don't need to match more than 6 characters in the lookahead. Matching only 6 here does no restrict the rest of the regular expression from matching more than 6.
• \d matches a digit, and (?=.*\\d) is a lookahead for one of them. This is why you are experiencing the problems you mentioned with strings like eN%{S$u).
• Even if the point above wasn't incorrect and the regular expression here was correct, you can combine the second lookahead with the .* that follows by just using .*\\d.*.

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