学习C#基础必看案例

            //Random随机数
            Random r = new Random();
            while (true)
            {
                int i = r.Next(1, 7);
                Console.WriteLine(i);
                Console.ReadKey();
                
            }






            //指定分隔符数组,返回不带空格符的字符串
            string str = "my         name                   is lei";
            char[] a = { ' ' };
            string[] b = str.Split(a,StringSplitOptions.RemoveEmptyEntries);
            for (int i = 0; i < b.Length; i++)
            {
                Console.WriteLine(b[i]);
            }
            Console.ReadKey();






            //倒序输出
            Console.WriteLine("请输入字符串");
            string a = Console.ReadLine();
            string[] d = a.Split(' ');
            for (int i = d.Length - 1; i >= 0;i-- )
            {
                Console.Write(d[i]+" ");
            }


            Console.ReadKey();




           //忽略大小写
            string a = "a";
            string b = "A";
            if (a.Equals(b,StringComparison.OrdinalIgnoreCase))
            {
                Console.WriteLine("一样的");
            }
            else { Console.WriteLine("不一样"); }
            
            Console.ReadKey();




            //字符替换
            string a = "2008-11-12";
            string[] b = a.Split('-');
            Console.WriteLine("{0}年{1}月{2}日", b);
            Console.ReadKey();




            //九九乘法表
            for (int i = 1; i <= 9;i++ )
            { 
                
                for (int j = 1; j <= i;j++ )
                {
                    
                    Console.Write("{0}X{1}={2:00}   ",i,j,i*j);
                }
                Console.WriteLine();
            }
            Console.ReadKey();




            //判断字符串内是否有指定的子字符串
            string[] strc = { "xxoo", "TMD", "和谐" };
            string a = Console.ReadLine();
            int i;
            for (i = 0; i < a.Length; i++)
            {
                if (a.Contains(strc[i]))
                {
                    break;
                }
            }
            if (i < a.Length)
            {
                Console.WriteLine("有非法字符");
            }
            else
            {
                Console.WriteLine("合法");
            }




            //水仙花规则
            //int i = 1 * 1 * 1 + 5 * 5 * 5+3 * 3 * 3;
            
            //求100_999的水仙花数
            for (int i = 100; i <= 999;i++ )
            { 
                //把个 十 百  分离出来
                int ge=i%10;
                int shi=i/10%10;
                int bai=i/100;
                //按照水仙花数规则判断
                if(i==ge*ge*ge+shi*shi*shi+bai*bai*bai )
                {
                    Console.WriteLine(i);
                }
            }
            Console.ReadKey();






           // 求1_100直接的偶数和
            int sum = 0;
            for (int i = 1; i <= 100;i++ )
            {
                //如果i能被2整除说明这个数是偶数
                if(i%2==0)
                {
                    sum += i;
                    Console.WriteLine(i);
                }
            }
            Console.WriteLine(sum);
            Console.ReadKey();
        }