0723循环语句

一.复习（选择语句）

首先复习昨天学习的if语句

 格式1   if（）{}

 格式2  if(){} else{}

 如果if满足，走if
 如果if不满足，就一定走else

 格式3 if(){}else   if(){}    else{}   多选一

 格式4  if的嵌套

 ////现在几点了，输出时间
            //Console.Write("请输入时间：");
            //int a = int.Parse(Console.ReadLine());
            //if (a <= 12)
            //{
            //    Console.WriteLine("现在是:" + a + "am");
            //}
            //else
            //{
            //    Console.WriteLine("现在是:" + (a-12) + "pm");
            //}
            //Console.ReadLine();

            //输入一个年份，判断是否是闰年（能被4整除却不能被100整除的年份。世纪年份能被400整除的是闰年）
            //Console.Write("请输入一个年份：");
            //double a = double.Parse(Console.ReadLine());
            //if (a % 4 == 0 && a % 100 != 0 || a % 100 == 0)
            //{
            //    Console.WriteLine("您输入的是闰年！");
            //}
            //else
            //{
            //    Console.WriteLine("您输入的不是闰年！");
            //}
            //Console.ReadLine();

            //输入一个100以内的整数，判断整数
            //Console.Write("请输入一个100以内的整数：");
            //double a = double.Parse(Console.ReadLine());
            //if (a == 100)
            //{
            //    Console.WriteLine("您输入的是三位整数！");
            //}
            //else if(a>=10&&a<100)
            //{
            //    Console.WriteLine("您输入的是两位整数！");
            //}
            //else
            //{
            //    Console.WriteLine("您输入的是一位整数！");
            //}
            //Console.ReadLine();

            //输入学生姓名，输入考试成绩
            //若是100，【恭喜**，满分通过！】
            //若是大于等于80小于100.【**，你很优秀，请继续保持】
            //若是大于等于60小于80，【**成绩良好】
            //大于等于50小于60，【**就差一点点，下次一定要至少及格】
            //小于50【**你是笨蛋吗】
            //Console.Write("请输入您的姓名：");
            //string b = Console.ReadLine();
            //Console.Write("请输入您的成绩：");
            //double a = double.Parse(Console.ReadLine());
            //if (a >= 0 && a <= 100)
            //{
            //    if (a==100)
            //    {
            //        Console.WriteLine("恭喜"+b+"，满分通过！");
            //    }
            //    else if(a<100&&a>=80)
            //    {
            //        Console.WriteLine(  b + "，你很优秀，请继续保持！");
            //    }
            //    else if (a < 80 && a >= 60)
            //    {
            //        Console.WriteLine(b + "成绩良好！");
            //    }
            //    else if(a>=50&&a<60)
            //    {
            //        Console.WriteLine(b + "就差一点点，下次一定要至少及格！");
            //    }
            //    else
            //    {
            //        Console.WriteLine( b + "你是笨蛋吗?");
            //    }
            //}
            //else
            //{
            //    Console.WriteLine("您的输入有误！");
            //}
            //Console.ReadLine();

            //有一组函数：y = x (x<1)；y = 2x -1  (1<=x<10)； y = 3x-11  (x>=10)。
            // 括号内是x的满足条件。
            // 实现功能，随意输入一个x值，输出y的值
            //Console.Write("请输入x的值：");
            //double x = double.Parse(Console.ReadLine());
            // if(x<1)
            // {
            //     Console.WriteLine("得到的y值为："+x);
            // }
            // else if (x >= 1 && x < 10)
            // {
            //     Console.WriteLine("得到的y值为：" +(2*x-1));
            // }
            // else
            // {
            //     Console.WriteLine("得到的y值为：" +(3*x-11) );
            // }

            // Console.ReadLine();

            //4.相亲过程：你有房子么？你有钱么？你有能力么？
            // 【结婚吧】【先买房子在结婚】【先赚钱再买房子再结婚】都没有【拜拜~~】
            //Console.Write("你有房子吗？");
            //string a = Console.ReadLine();
            //if (a == "有")
            //{
            //    Console.WriteLine("结婚吧！");
            //}
            //else
            //{
            //    Console.Write("你有钱吗？");
            //    string b = Console.ReadLine();
            //    if (b == "有")
            //    {
            //        Console.WriteLine("先买房子再结婚。");
            //    }
            //    else
            //    {
            //     Console.Write("你有能力吗？");
            //     string c = Console.ReadLine();
            //     if (c == "有")
            //     {
            //         Console.WriteLine("先赚钱再买房子再结婚。");
            //     }
            //     else
            //     {
            //         Console.WriteLine("拜拜~");
            //     }
            //    }
            //}
            //Console.ReadLine();

            //方程ax2+bx+c=0;一元二次方程。求根
            //△=b2-4ac；若△<0方程无实根
            //若△>0，方程有两个不相同的实根x1   x2
            //若△=0，方程有两个相同的实根
            //Console.Write("请输入a的值：");
            //double a = double.Parse(Console.ReadLine());
            //Console.Write("请输入b的值：");
            //double b = double.Parse(Console.ReadLine());
            //Console.Write("请输入c的值：");
            //double c = double.Parse(Console.ReadLine());
            //double de=b*b-4*a*c;
            //if(a!=0)
            //{
            //    if (de > 0)
            //    {
            //        Console.WriteLine("此方程有两个不同实数根，分别为x1="+((-b-de)/(2*a))+"x2="+((-b+de)/(2*a)));
            //    }
            //    else if (de == 0)
            //    {
            //        Console.WriteLine("此方程有两个相同实数根，为x1=x2=" + ((-b - de) / (2 * a)));
            //    }
            //    else
            //    {
            //        Console.WriteLine("此方程没有实数根");
            //    }
            //}
            //else
            //{
            //    Console.WriteLine("此方程不是一元二次方程");
            //}

            //Console.ReadLine();

            //输入年月日，查看格式是否正确
            //Console.Write("请输入年份：");
            //int year = int.Parse(Console.ReadLine());
            // if(year>=0&&year<=9999)
            // {
            //     Console.Write("请输入月份：");
            //     int month=int.Parse(Console.ReadLine());
            //     if (month >= 0 && month <= 12)
            //     {
            //         Console.Write("请输入日期：");
            //         int day = int.Parse(Console.ReadLine());
            //         if (day >= 1 && day <= 31)
            //         {
            //           if(month==1||month==3||month==5||month==7||month==8||month==10||month==12)
            //           {
            //              Console.WriteLine("您输入的日期格式正确，日期为："+year+"年"+month+"月"+day+"日。");
            //           }
            //           else if(month==4||month==6||month==9||month==11)
            //           {
            //               if (day == 31)
            //               {
            //                   Console.WriteLine("您输入的日期格式错误！");
            //               }
            //               else
            //               {
            //                   Console.WriteLine("您输入的日期格式正确，日期为：" + year + "年" + month + "月" + day + "日。");
            //               }
            //           }
            //           else if(month==2)
            //           {
            //               if (day < 30)
            //               {
            //                   if (day == 29)
            //                   {
            //                       if (year % 4 == 0 && year % 100 != 0 || year % 100 == 0)
            //                       {
            //                           Console.WriteLine("您输入的日期格式正确，日期为：" + year + "年" + month + "月" + day + "日。");
            //                       }
            //                       else
            //                       {
            //                           Console.WriteLine("您输入的日期格式错误！");
            //                       }
            //                   }
            //                   else
            //                   {
            //                       Console.WriteLine("您输入的日期格式正确，日期为：" + year + "年" + month + "月" + day + "日。");
            //                   }
            //               }
            //               else
            //               {
            //                   Console.WriteLine("您输入的日期格式错误！");
            //               }
            //           }
            //         }
            //         else
            //         {
            //             Console.WriteLine("您输入的日期有错！");
            //         }
            //     }
            //     else
            //     {
            //         Console.WriteLine("您输入的月份有错！");
            //     }
            // }
            // else
            // {
            //     Console.WriteLine("您输入的年份有错！");
            // }
            // Console.ReadLine();

            //标准体重：
            //男士体重=身高-100±3
            //女士体重=身高-110±3
            //Console.Write("请输入您的性别：");
            //string a = Console.ReadLine();
            //Console.Write("请输入您的身高：");
            //double b = double.Parse(Console.ReadLine());
            // Console.Write("请输入您的体重：");
            //double c = double.Parse(Console.ReadLine());
            //if(a=="男")
            //{
            //    if (c >= (b - 100 - 3) && c <= (b - 100 + 3))
            //    {
            //        Console.WriteLine("您的体重标准！");
            //    }
            //    else
            //    {
            //        if (c < (b - 100 - 3))
            //      {
            //          Console.WriteLine("您偏瘦！");
            //      }
            //      else
            //      {
            //          Console.WriteLine("您偏胖！");
            //      }
            //    }
            //}
            //else if (a=="女")
            //{
            //    if (c >= (b - 110 - 3) && c <= (b - 110 + 3))
            //    {
            //        Console.WriteLine("您的体重标准！");
            //    }
            //    else
            //    {
            //        if (c < (b - 110 - 3))
            //        {
            //            Console.WriteLine("您偏瘦！");
            //        }
            //        else
            //        {
            //            Console.WriteLine("您偏胖！");
            //        }
            //    }
            //}
            //else
            //{
            //    Console.WriteLine("您的输入有误！");
            //}
            //Console.ReadLine();

            //输入三个数，由小到大排列输出
            //Console.Write("请输入第一个数：");
            //double a = double.Parse(Console.ReadLine());
            //Console.Write("请输入第一个数：");
            //double b = double.Parse(Console.ReadLine());
            //Console.Write("请输入第一个数：");
            //double c = double.Parse(Console.ReadLine());
            //double d;
            //if(a>=b)
            //{
            //    d = a;
            //    if (d >=c)
            //    {
            //        if (c >=b)
            //        {
            //            Console.WriteLine(a + ">" + c + ">" + b);
            //        }
            //        else
            //        {
            //            Console.WriteLine(a + ">" + b + ">" + c);
            //        }
            //    }
            //    else
            //    {
            //            Console.WriteLine(c + ">" + a + ">" + b);
            //        }
            //}
            //else
            //{
            //    d = b;
            //    if (d >=c)
            //    {
            //        if (a >= c)
            //        {
            //            Console.WriteLine(b + ">" + a + ">" + c);
            //        }
            //        else
            //        {
            //            Console.WriteLine(b + ">" + c + ">" + a);
            //        } 
            //    }
            //    else
            //    {
            //        Console.WriteLine(c + ">" + b + ">" + a);
            //    }
            //}
            //Console.ReadLine();
 

 二.循环语句

for（；；）{}

 //语句的分类：顺序，分支，循环语句
             //循环语句
            //for (int i=1;i<=10 ;i++ )
            //{
            //    Console.WriteLine("你好！");
            //}
            //Console.ReadLine();

            ////死循环
            ////for (; ; )
            ////{
            ////     Console.WriteLine("nihao");
            ////}

            //输入一个正整数n，求1-n的和
            //Console.Write("请输入一个正整数：");
            //int a = int.Parse(Console.ReadLine());
            //int b = 0;
            //for (int i = 1; i <= a; i++)
            //{
            //    b = b + i; //b+=i;
            //}
            //Console.WriteLine(b);
            //Console.ReadLine();

            // 输入一个数，求阶乘
            //Console.Write("请输入一个正整数：");
            //int a = int.Parse(Console.ReadLine());
            //int b = 1;
            //for (int i = 1; i <= a; i++)
            //{
            //    b *= i;
            //}
            //Console.WriteLine(b);
            //Console.ReadLine();

            // 输入一个数，求阶乘的和
            //Console.Write("请输入一个正整数：");
            //int a = int.Parse(Console.ReadLine());
            //int b = 1; int c=0;
            //for (int i = 1; i <= a; i++)
            //{
            //    b *= i;
            //    if(i==4) //不进行4！
            //    {
            //        continue;//终止本次循环，继续下次循环
            //    }
            //     c += b;
            //}
            //Console.WriteLine(c);
            //Console.ReadLine();

            if嵌套for    for嵌套if
            //一个游戏，前20关是每一关自身的分数，
            //21-30关每一关是10分
            //31-40关，每一关是20分
            //41-49关，每一关是30分
            //50关，是100分
            //输入你现在闯到的关卡数，求你现在拥有的分数
            //Console.Write("请输入您的关卡：");
            //int a = int.Parse(Console.ReadLine());
            //int b = 0;
            //if (a < 1 && a > 50)
            //{
            //    Console.WriteLine("您输入的关卡数有误！");
            //}
            //else
            //{
            //    if (a <= 20)
            //    {
            //        for (int i = 1; i <= a; i++)
            //        {
            //            b += i;
            //        }
                  
            //    }
            //    else if (a >= 21 && a <= 30)
            //    {
            //        for (int i = 1; i <= 20; i++)
            //        {
            //            b += i;
            //        }
            //        for (int i = 21; i <= a; i++)
            //        {
            //            b += 10;
            //        }
                   
            //    }
            //    else if (a >= 31 && a <= 40)
            //    {
            //        for (int i = 1; i <= 20; i++)
            //        {
            //            b += i;
            //        }
            //        for (int i = 21; i <= 30; i++)
            //        {
            //            b += 10;
            //        }
            //        for (int i = 31; i <= a; i++)
            //        {
            //            b += 20;
            //        }
                  
                  
            //    }
            //    else if (a >= 41 && a <= 49)
            //    {
            //        for (int i = 1; i <= 20; i++)
            //        {
            //            b += i;
            //        }
            //        for (int i = 21; i <= 30; i++)
            //        {
            //            b += 10;
            //        }
            //        for (int i = 31; i <= 40; i++)
            //        {
            //            b += 20;
            //        }
            //        for (int i = 41; i <= 49; i++)
            //        {
            //            b += 30;
            //        }
                  
            //    }
            //    else
            //    {
            //          for (int i = 1; i <= 20; i++)
            //        {
            //            b += i;
            //        }
            //        for (int i = 21; i <= 30; i++)
            //        {
            //            b += 10;
            //        }
            //        for (int i = 31; i <= 40; i++)
            //        {
            //            b += 20;
            //        }
            //        for (int i = 41; i <= 49; i++)
            //        {
            //            b += 30;
            //        }
            //        b += 100;
            //    }
            //}
            //    Console.WriteLine(b);
            //    Console.ReadLine();

            //Console.Write("请输入您的关卡：");
            //int a = int.Parse(Console.ReadLine());
            //int b = 0;
            //if (a < 1 && a > 50)
            //{
            //    Console.WriteLine("您输入的关卡数有误！");
            //}
            //else
            //{
            //    for (int i = 1; i <= a; i++)
            //    {
            //        if (i <= 20)
            //        {
            //            b += i;
            //        }
            //        else if ( i <= 30)
            //        {
            //            b += 10;
            //        }
            //        else if ( i <= 40)
            //        {
            //            b += 20;
            //        }
            //        else if ( i <= 49)
            //        {
            //            b += 30;
            //        }
            //        else
            //        {
            //            b = b + 100;
            //        }
            //    }
            //}
            //Console.WriteLine("您的分数是：" + b);
            //Console.ReadLine();

             //案例：找出100以内与7有关的数并打印、
             //（1）.从1找到100
             //（2）.找出与7有关的数
             //      个位数是7 a%10==7
             //      十位数是7 a/10 ==7
             //      能被7整除 a%7 ==0
            //for (int i=1;i<=100&&i>0;i++)
            //{
            //    if (i % 10 == 7 )
            //    {
            //        Console.WriteLine(i+"个位数为7。");
            //    }
            //    else if (i / 10 == 7)
            //    {
            //        Console.WriteLine(i+"十位数为7。");
            //    }
            //    else if(i%7==0)
            //    {
            //        Console.WriteLine(i+"为7的倍数。");
            //    }
            //}
            //Console.ReadLine();
            //for (int i = 1; i <= 100 && i > 0; i++)
            //{
            //    if (i % 10 == 7||i / 10 == 7||i % 7 == 0)
            //    {
            //        Console.Write(i + " ");  //水平制表符
            //    }
            //}
            //Console.ReadLine();