Count regex replaces (C#)

Question

Is there a way to count the number of replacements a Regex.Replace call makes?

E.g. for Regex.Replace(\"aaa\", \"a\", \"b\"); I want to get the number 3

Answer 1

You can use a MatchEvaluator that runs for each replacement, that way you can count how many times it occurs:

int cnt = 0;
string result = Regex.Replace("aaa", "a", m => {
  cnt++;
  return "b";
});

The second case is trickier as you have to produce the same result as the replacement pattern would:

int cnt = 0;
string result = Regex.Replace("aaa", "(?aa?)", m => {
  cnt++;
  return m.Groups["test"] + "b";
});