全角转半角

    class Program
    {
        static void Main(string[] args)
        {

            string input = Console.ReadLine();

            while (input.ToLower()!="exit")
            {
                string mess = ToDBC(input);

                Console.WriteLine(mess);

                input = Console.ReadLine();
            }
            Console.ReadLine();
        }


        /// <summary>
        /// 将字符串转为半角
        /// </summary>
        /// <param name="input"></param>
        /// <returns></returns>
        public static string ToDBC(string input)
        {
            char[] c = input.ToCharArray();
            for (int i = 0; i < c.Length; i++)
            {
                if (c[i] == 12288)
                {
                    c[i] = (char)32;
                    continue;
                }
                if (c[i] > 65280 && c[i] < 65375)
                    c[i] = (char)(c[i] - 65248);
            }
            return new String(c);
        }
    }

 效果图如下：