字符串 C# 中正则表达式的第 n 个匹配项的索引

Question

Can anyone please help me in finding the index of 5th match of the Regex (matches * not inside double quotes) in the following string?

ABC*DEF*PQR*"LMN*ABC"*XYZ*MNO*ABC*XYZ

ie 25 (just before MNO)

please help with the C# code to write the value 25 on the console output.

I used the Regex: \\*(?=([^"]*"[^"]*")*[^"]*$)

Thanks!

Answer 1

Following is a regex that will solve the problem. Only limitation is if you enter more than present double quotes in the string, it will lead to catastrophic backtracking

(?:(?:(?:[^*"]*)(?:"[^"]*")*)*(\*)){5}

Regex Demo

Answer 2

string text = "ABC*DEF*PQR*\"LMN* ABC\"*XYZ*MNO*ABC*XYZ";
string pattern = "\\*(?=([^\"]*\"[^\"]*\")*[^\"]*$)";

var matches = Regex.Matches(text, pattern);

Console.WriteLine(matches[4].Index); // indexing from 0, so 4, not 5