Right around the time that C# 3.0 came out, I was working on a project that required me to count the occurrences of a given character in a string.  This was being done within a highly repetitive loop so it was imperative that it be as efficient as possible.  I’ve always wanted to do performance testing on this and I finally got around to it recently and thought I’d post the results here.

There isn’t anything in the string class that gives us the functionality to count how many times an individual character occurs.  I really hadn’t looked at Lambda expressions and someone at work suggested the following:

    string      testStr = "this,string,has,commas,in,it"            ;
    int         howMany = testStr.ToCharArray().Count(x => x == ',');

I thought, OK, nice and compact (all on one line) but I really didn’t understand it at the time and so went with a brute force way of doing it:

  string      testStr = "this,string,has,commas,in,it";
  int         howMany = 0                             ;
  for (int j = 0; j < testStr.Length; ++j)
  {
      if (testStr[j] == ',')
      {
          ++howMany;
      }
  }

And I’m glad I did.  Here’s why…

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