Question

While answering this question C# Regex Replace and * the point was raised as to why the problem exists. When playing I produced the following code:

    string s = Regex.Replace(".A.", "\w*", "B");
    Console.Write(s);

This has the output: B.BB.B

I get that the 0 length string is match before and after the . character, but why is A replaced by 2 Bs.

I could understand B.BBB.B as replacing zero-length strings either side of A or B.B.B
But the actual result confuses me – any help appreciated.

Or as AakashM has put it:

Why is Regex.Matches("A", "\w*").Count equal to 2, not 1 or 3 ?

Answer 1

because \w* is a greedy regex and it tries to find biggest sequence. So it matches "nothing" before dot, then "nothing"A between two dots then "nothing" before second dot and finally "nothing" after the second dot.