程序代码：

        /// <summary>
        /// 输入一个十进制 返回一个二进制
        /// </summary>
        /// <param name="d"></param>
        /// <returns>装换成的二进制数</returns>
        public static string DtoB(int d)
        {
            string b = "";
            //判断该数如果小于2，则直接输出
            if (d < 2)
            {
                b = d.ToString();
            }
            else
            {
                int c;
                int s = 0;
                int n = d;
                while (n >= 2)
                {
                    s++;
                    n = n / 2;
                }
                int[] m = new int[s];
                int i = 0;
                do
                {
                    c = d / 2;
                    m[i++] = d % 2;
                    d = c;
                } while (c >= 2);
                b = d.ToString();
                for (int j = m.Length - 1; j >= 0; j--)
                {
                    b += m[j].ToString();
                }
            }
            return b;
        }