利用goto，印出正三角形

            int triangle1 = 1;
            int triangle2 = 1;
            for1:
            triangle2 = 1;
            for2:
            triangle2 += 1;
            Console.Write(0);
            if (triangle2 <= triangle1)
                goto for2;
            triangle1 += 1;
            Console.WriteLine();
            if (triangle1 < 10)
                goto for1;