题一：九九乘法表的答案                //正三角            for (int i = 1; i < 10; i++)            {                for (int j = 1; j <= i; j++)                {                    Console.Write("{0}*{1}={2} ", j, i, i * j);                }                Console.WriteLine();            }            Console.ReadLine();            //倒三角            for (int i = 9; i >= 1; i--)            {                for (int j = i; j >= 1; j--)                {                    Console.Write("{0}*{1}={2} ", i, j, i * j);  //不换行                }                Console.WriteLine(); //换行            }            Console.ReadLine();              反倒三角            string sd = string.Empty;            for (int i = 9; i >= 1; i--)            {                for (int j = i; j >= 1; j--)                {                    string k = "  ";                    if (j * i > 9)                    {                        k = " ";                    }                    Console.Write("{0}*{1}={2}{3}", j, i, i * j, k);                }                Console.WriteLine();                sd += "       ";                Console.Write(sd);            }            Console.ReadLine();题二:            //星星图1            Console.WriteLine("请输入您想看到的星星行数");            int num = Convert.ToInt32(Console.ReadLine());            for (int hang = 1; hang <= num; hang++)            {                string k = String.Empty;                string x = String.Empty;                for (int kong = 1; kong <= num - hang; kong++)                {                    k += " ";                }                for (int xing = 1; xing <= hang; xing++)                {                    x += "* ";                }                Console.WriteLine(k + x + k);            }            Console.ReadLine();            //星星图(倒三角星星)            Console.WriteLine("请输入您想看到的星星行数");            int num = Convert.ToInt32(Console.ReadLine());            for (int hang = 1; hang <= num; hang++)            {                string k = String.Empty;                string x = String.Empty;                for (int kong = 1; kong <= hang - 1; kong++)                {                    k += " ";                }                for (int xing = 1; xing <= num - hang + 1; xing++)                {                    x += "* ";                }                Console.WriteLine(k + x + k);            }            Console.ReadLine();            ////星星图四            Console.WriteLine("请输入您想看到的星星行数");            int num = Convert.ToInt32(Console.ReadLine());            int gg = num * 2;            for (int hang = 1; hang <= num; hang++)            {                string k = String.Empty;                string x = String.Empty;                for (int kong = 1; kong <= gg - 2 * hang; kong++)                {                    k += " ";                }                for (int xing = 1; xing <= hang; xing++)                {                    x += "* ";                }                Console.WriteLine(k + x);            }            Console.ReadLine();            //星星图（倒三角*）            Console.WriteLine("请输入您想看到的星星行数");            int num = Convert.ToInt32(Console.ReadLine());            int gg = num * 2;            for (int hang = 1; hang <= num; hang++)            {                string k = String.Empty;                string x = String.Empty;                for (int kong = 1; kong <= 2 * (hang - 1); kong++)                {                    k += " ";                }                for (int xing = 1; xing <= num - hang + 1; xing++)                {                    x += "* ";                }                Console.WriteLine(k + x);            }            Console.ReadLine();           //星星图（最终效果菱形）            int a = int.Parse(Console.ReadLine());            for (int i = 0; i <= a; i++)            {                string k = String.Empty;                string x = String.Empty;                for (int s = 0; s < a - i + 1; s++)                {                    k += " ";                }                for (int d = 0; d < 2 * i - 1; d++)                {                    x += "*";                }                Console.WriteLine(k + x + k);            }            for (int i = a - 1; i > 0; i--)            {                string k = String.Empty;                string x = String.Empty;                for (int s = 0; s < a - i + 1; s++)                {                    k += " ";                }                for (int d = 0; d < 2 * i - 1; d++)                {                    x += "*";                }                Console.WriteLine(k + x + k);            }            Console.ReadLine();          //星星图（显示 图四效果/图五效果）最终显示图六效果          for (int i = 1; i <= 4; i++)            {                for (int j = 1; j <= 4 - i; j++)                {                    Console.Write(" ");                }                for (int k = 1; k <= i; k++)                {                    Console.Write("*");                }                Console.WriteLine("");            }            for (int i = 4; i >= 1; i--)            {                for (int j = 1; j <= 4 - i; j++)                {                    Console.Write(" ");                }                for (int k = 1; k <= i; k++)                {                    Console.Write("*");                }                Console.WriteLine("");            }            Console.ReadKey();