How to check repeated letters in a string c#

Question

I am creating a program that checks repeated letters in a string.

For Example:

wooooooooooow
happpppppppy

This is my

Answer 1

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Delegate
{
    class Program
    {
       public int repeatcount(string str,char ch)
        {

            var count = 0;
            for (int i = 0; i