/// <summary>
    /// 利用异或来判断奇偶性
    /// 先把十进制转换为二进制后再利用二进制位逐个异或来判断结果奇偶性
    /// h：当h为０时，flag为true则为奇数，反之亦然
    /// </summary>
    class Program
    {
        static void Main(string[] args)
        { 
            int a,h; 
            bool flag=false;
            string b;
            char[] c = { };

            while (true)
            {
                h = 0;
                Console.WriteLine("请输入一个十进制数：");
                try
                {
                    a = Convert.ToInt32(Console.ReadLine());

                }
                catch
                {
                    Console.WriteLine("输入不正确，正常退出！");
                    break;
                }

                b = Convert.ToString(a, 2);
                c = b.ToCharArray();    
                for (int k = 0; k < c.Length - 1; k++)
                {
                    h ^= c[k] ^ c[k + 1];
                    if (h == 0)
                    {
                        flag = false;
                    }
                    else
                    {
                        flag = true;
                    }

                }
                if (flag)
                {
                    Console.WriteLine("偶数\n");
                }
                else
                {
                    Console.WriteLine("奇数\n");
                }

            }
            Console.ReadKey();
        }
    }

b = Convert.ToString(a, 2);
c = b.ToCharArray();
for (int k = 0; k < c.Length - 1; k++)
{
    h ^= c[k] ^ c[k + 1];
}
if (h != 0)
{
    Console.WriteLine("偶数\n");
}
else
{
    Console.WriteLine("奇数\n");
}

------解决方案--------------------
while (true)
{
      string s = Console.ReadLine();
      int x = 0;
      if (!int.TryParse(s, out x))
          continue;
      Console.WriteLine((x ^ (x + 1)) == 1 ? "偶数" : "奇数");
}