如何将全角输入的电话号码转换为半角的？
如１８８３８２８４８５８转换成
18838284858？

public static String ToSBC(String input)
        {            
            char[] c = input.ToCharArray();
            for (int i = 0; i < c.Length; i++)
            {
                if (c[i] == 32)
                {
                    c[i] = (char)12288;
                    continue;
                }
                if (c[i] < 127)
                    c[i] = (char)(c[i] + 65248);
            }
            return new String(c);
        }
               
        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);
        }
        static void Main(string[] args)
        {
            string strSBC = "１８８３８２８４８５８";
            string result = ToDBC(strSBC);
            Console.WriteLine(result);
            Console.ReadKey();         
        }