Charecter Count in a string

Hi friends,
I haven't found any separate function in c# to find the no of occurrence of one letter in one string.

Here is a simple function to find out no of occurrence of a character in string easily

static int CountChars(string value,char key)
        {
            int count = 0;
            foreach (char c in value)
            {
                if (c==key)
                {
                    result++;
                   
                }
                
            }
            return count; 
        }