C#实现大数相乘

public string zz(string a, string b)
        {
            char[] chara = a.ToCharArray();
            char[] charb = b.ToCharArray();
            int[] inta = Array.ConvertAll(chara, new Converter<char, int>(delegate(char g) { return int.Parse(g.ToString()); }));
            int[] intb = Array.ConvertAll(charb, new Converter<char, int>(delegate(char g) { return int.Parse(g.ToString()); }));
            int x = a.Length;
            int y = b.Length;
            int[] c = new int[x + y];
            while (x > 0) {
                x--;
                y = b.Length;
                while (y > 0) {
                    y--;
                    c[x + y + 1] = c[x + y + 1] + inta[x] * intb[y];
                }
            }
            string f = string.Join("", Array.ConvertAll(zzz(c, c.Length - 1), new Converter<int, string>(delegate(int g) { return g.ToString(); })));
            return f.Substring(0, 1).Replace("0", "") + f.Substring(1, f.Length - 1);
        }


        public int[] zzz(int[] arr, int n)
        {
            if (n > 0)
            {
                arr[n - 1] += arr[n] / 10;
                arr[n] %= 10;
                return zzz(arr, n - 1);
            }
            return arr;
        }