字符串中截取b的数量

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

namespace 字符串中截取b的数量
{
    class Program
    {
        static void Main(string[] args)
        {
            int i = 0;
            Console.WriteLine("请输入：");
            string B = Console.ReadLine();
            B = B.ToLower();

            if (B.IndexOf("b") < 0)

            {
                Console.WriteLine("没有b");
            }
            else
                {
                    int c = B.Length;
                    for (i = 0; i <= c; i++)
                    {
                        int b = B.IndexOf("b");
                        if (b < 0)
                            break;
                        B = B.Substring(b + 1);
                    }
                    Console.WriteLine("字符中含有" + i + "个b(B)");


                }
                Console.ReadLine();

            }
    }
}