for循环

            Console.Write("请输入数字：");
            int n = int.Parse(Console.ReadLine());
            for (int i = 1; i <= n; i++) 
            {
                for (int t = 1; t <i ;t++ ) 
                {
                    Console.Write("。");
                }
                for (int a = n-i+1; a >=1;a--)
                {
                    Console.Write("◎");
                }
                Console.Write("
");

            }
            Console.ReadLine();

打印菱形

            Console.Write("请输入数字：");
            int n = int.Parse(Console.ReadLine());
            for (int i = 1; i <= n; i++) 
            {
                for (int t = 1; t <=n-i ;t++ ) 
                {
                    Console.Write("。");
                }
                for (int a = 1; a <=2*i-1;a++)
                {
                    Console.Write("★");
                }
                Console.Write("
");

            }
          
            for (int m = 1; m < n; m++)
            {
                for (int p = 1; p<= m; p++)
                {
                    Console.Write("。");
                }
                for (int k= 1; k<= 2 * (n-m) - 1; k++)
                {
                    Console.Write("★");
                }
                Console.Write("
");

            }
            Console.ReadLine();