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从C中的字符串提取最后一个匹配项#

capture-group lookaround regex .net c#

knittl · 技术社区 · 15 年前

我在表格中有字符串 [abc].[some other string].[can.also.contain.periods].[our match]

i now want to match the string "our match" (i.e. without the brackets), so i played around with lookarounds and whatnot. i now get the correct match, but i don't think this is a clean solution.

(?<=\.?\[)     starts with '[' or '.['
([^\[]*)      our match, i couldn't find a way to not use a negated character group
              `.*?` non-greedy did not work as expected with lookarounds,
              it would still match from the first match
              (matches might contain escaped brackets)
(?=\]$)       string ends with an ]

语言是.NET/C。如果有一个简单的解决方案不涉及regex,我也很高兴知道

what really irritates me is the fact, that i cannot use (.*?) 要捕获字符串,因为它似乎不是贪婪的,不适用于lookbehinds。

我也尝试过: Regex.Split(str, @"\]\.\[").Last().TrimEnd(']'); 但是我也不是很喜欢这个解决方案

4 回复 | 直到 15 年前

Jacob Poul Richardt 15 年前

下面将介绍这个技巧。假设字符串在最后一次匹配之后结束。

string input = "[abc].[some other string].[can.also.contain.periods].[our match]";

var search = new Regex("\\.\\[(.*?)\\]$", RegexOptions.RightToLeft);

string ourMatch = search.Match(input).Groups[1]);

David_001 15 年前

Assuming you can guarantee the input format, and it's just the last entry you want, LastIndexOf 可以使用:

string input = "[abc].[some other string].[can.also.contain.periods].[our match]";

int lastBracket = input.LastIndexOf("[");
string result = input.Substring(lastBracket + 1, input.Length - lastBracket - 2);

Rox 15 年前

使用string.split():

string input = "[abc].[some other string].[can.also.contain.periods].[our match]";
char[] seps = {'[',']','\\'};
string[] splitted = input.Split(seps,StringSplitOptions.RemoveEmptyEntries);

Edit: the array will have the string inside [] and then . and so on, so if you have a variable number of groups, you can use that to get the value you want (or remove the strings that are just '.')

编辑后将反斜杠添加到分隔符,以处理类似'\[abc\]

edit2:对于嵌套的[]:

string input = @"[abc].[some other string].[can.also.contain.periods].[our [the] match]";
string[] seps2 = { "].["};
string[] splitted = input.Split(seps2, StringSplitOptions.RemoveEmptyEntries);

您在最后一个元素(索引3)中的[匹配]必须删除多余的]

polygenelubricants 15 年前

您有几个选项:

RegexOptions.RightToLeft -是的,.net regex可以做到!用它!
Match the whole thing with greedy prefix, use brackets to capture the suffix that you're interested in
- 一般说来, pattern 变成 .*(pattern)
- 在这种情况下, .*\[([^\]]*)\] , then extract what \1 捕获(捕获) see this on rubular.com )