负向前瞻/后视 [英] Negative lookahead/lookbehind

问题描述

我正在尝试制作一个声明，让我识别我的客户输入的格式错误的文本。格式良好的语句如下所示：

I am trying to craft a statement that will let me identity malformed text entered by my clients.  A well-formed statement will look like the following:

##< 1到50个字母字符和0到5个数字> ##

##<1 to 50 alpha characters and 0 to 5 numbers>##

我提出的陈述如下，但似乎不起作用。任何帮助将不胜感激。

The statement I've come up with is the following, but it doesn't appear to work.  Any help would be appreciated.

\＃\＃（？！[a-zA-Z] {1,50}（ ？:: [\d] {0,5}）\＃\＃）|（小于？！\？＃\＃[A-ZA-Z] {1,50}（:: [\ d] {0,5}）？）\＃\＃

\#\#(?![a-zA-Z]{1,50}(?::[\d]{0,5})?\#\#)|(?<!\#\#[a-zA-Z]{1,50}(?::[\d]{0,5})?)\#\#

推荐答案

模式的第一部分使用 Match Invalidator ？这意味着如果匹配发生，取消停止任何更多匹配。如果您使用有效格式，则创建一个看起来像这样的模式，并且无法匹配任何其他模式。只用？！当一个人有一个有效的格式，但内部有问题或匹配过程需要停止。

使用Match invalidator查看我的博客和SSN示例：正则表达式（正则表达式）匹配.Net中的无效者（？！）。 HTH

The first part of the pattern uses the Match Invalidator ?! which means if the match occurs, cancel stop any more matching. If you have a valid format create a pattern which looks like that and fails to match on anything else. Only use the ?! when one has a valid format but internally something is wrong or the matching process needs to stop .

Check out my blog and a SSN example using the Match invalidator: Regular Expression (Regex) Match Invalidator (?!) in .Net . HTH

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