7.23 学习 循环语句

循环语句

循环四要素：初始条件，循环条件，循环体，状态改变。
for(初始条件;循环条件;状态改变)
{
 循环体
}
break ——中断循环，跳出循环
continue——停止本次循环，进入下次循环

.输入一个整数，计算从1加到这个数的结果
int sum = 0;
Console.WriteLine("请输入一个正整数");
int a = int.Parse(Console.ReadLine());
for(int i =0; i<=a ;i++)
{
 sum += i;
}
Console.WriteLine("从1加到"+a+"的结果是："+sum);
Console.ReadLine();

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

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
            两种做法：if嵌套for    for嵌套if
            Console.Write("请输入您现在闯到的关卡数：");
            int guan = int.Parse(Console.ReadLine());
            if (guan >= 1 && guan <= 50)
            {
                int sum = 0;
                if (guan <= 20)
                {
                    for (int i = 1; i <= guan; i++)
                    {
                        sum += i;
                    }
                }
                else if (guan <= 30)
                {
                    for (int i = 1; i <= 20; i++)
                    {
                        sum += i;
                    }
                    for (int i = 21; i <= guan; i++)
                    {
                        sum += 10;
                    }
                }
                else if (guan <= 40)
                {
                    for (int i = 1; i <= 20; i++)
                    {
                        sum += i;
                    }
                    for (int i = 21; i <= 30; i++)
                    {
                        sum += 10;
                    }
                    for (int i = 31; i <= guan; i++)
                    {
                        sum += 20;
                    }
                }
                else if (guan <= 49)
                {
                    for (int i = 1; i <= 20; i++)
                    {
                        sum += i;
                    }
                    for (int i = 21; i <= 30; i++)
                    {
                        sum += 10;
                    }
                    for (int i = 31; i <= 40; i++)
                    {
                        sum += 20;
                    }
                    for (int i = 41; i <= guan; i++)
                    {
                        sum += 30;
                    }
                }
                else//50关
                {
                    for (int i = 1; i <= 20; i++)
                    {
                        sum += i;
                    }
                    for (int i = 21; i <= 30; i++)
                    {
                        sum += 10;
                    }
                    for (int i = 31; i <= 40; i++)
                    {
                        sum += 20;
                    }
                    for (int i = 41; i <= 49; i++)
                    {
                        sum += 30;
                    }
                    sum += 100;
                }
                Console.WriteLine(sum);
            }
            else
            {
                Console.WriteLine("输入有误！");
            }
            Console.ReadLine();