C#第五章学习代码

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace _5._1_分支语句之if语句
{
    class Program
    {
        static void Main(string[] args)
        {
            //判断变量a中存放数值与10的关系
            Console.WriteLine("请输入数值，判断它与10的关系：");
            int a = int.Parse(Console.ReadLine());
            //int.Parse用于将屏幕输入的语句转换为整型
            if (a<10)
            {
                Console.WriteLine("您输入的数什小于10");
            }
           else if (a==10)
            {
                Console.WriteLine("您输入的数值等于10");
            }
           else//如果前边的if语句一条也没有执行，那就执行else语句
           //如果执行了其中一条if句语，那就不会执行else语句
            {
                Console.WriteLine("您输入的数值大于10");
            }
            Console.ReadKey();
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace _5._2_分支语句之switch语句
{
    class Program
    {
        static void Main(string[] args)
        {
            //输入1显示星期一，依次类推
            Console.WriteLine("请输入月分数");
            int month = int.Parse(Console.ReadLine());
            //if (week == 1) Console.WriteLine("星期一");
            //if (week == 2) Console.WriteLine("星期二");
            //if (week == 3) Console.WriteLine("星期三");
            //if (week == 4) Console.WriteLine("星期四");
            //if (week == 5) Console.WriteLine("星期五");
            //if (week == 6) Console.WriteLine("星期六");
            //if (week == 7) Console.WriteLine("星期日");

            //switch (week)
            //{
            //    case 1: Console.WriteLine("星期一"); break;
            //    case 2: Console.WriteLine("星期二"); break;
            //    case 3: Console.WriteLine("星期三"); break;
            //    case 4: Console.WriteLine("星期四"); break;
            //    case 5: Console.WriteLine("星期五"); break;
            //    case 6: Console.WriteLine("星期六"); break;
            //    case 7: Console.WriteLine("星期日"); break;
            //    default: Console.WriteLine("您的输入有误"); break;



            //}

            //判断2015年每个月份的天数
            //31天：1、3、5、7、8、10、12
            //30天：4、6、9、11
            //28天：2

            switch(month)
{
                case 2: Console.WriteLine("本月有28天");break;
                case 4:
                case 6:
                case 9:
                case 11:
                    Console.WriteLine("本月有30天");break;
                default: Console.WriteLine("本月有31天");break;

            }


            Console.ReadLine();

        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace _5._3分支语句之三元运算符
{
    class Program
    {
        static void Main(string[] args)
        {
            //提示用户进行输入
            Console.WriteLine("请输入您需要比较的数值");
            int num = int.Parse(Console.ReadLine());
            Console.WriteLine(num < 10 ? "您输入的数值小于10" : "您输入的数值大于等于10");
            Console.ReadKey();
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace _5._4_迭代语句之while语句
{
    class Program
    {
        static void Main(string[] args)
        {
            //输出1-50到屏幕上
            //Console.WriteLine(1);
            //Console.WriteLine(2);
            //Console.WriteLine(3);
            //利用while可以大量简化重复执行的代码

            int num = 1;
            while (num <= 50)
            {
                Console.WriteLine(num);
                num++;

            }
            Console.ReadKey();
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace _5._5_迭代语句之do._.while语句
{
    class Program
    {
        static void Main(string[] args)
        {

            //输出1-50到屏幕上
            //int num = 0;
            //do
            //{
            //    num++;
            //    Console.WriteLine(num);
            //} while (num !=0);
            double Balance=0;
            double Rate = 0;
            int Year = 0;
            double TargetBalance = 0;
            Console.WriteLine("请输入您的本金");
            Balance = double.Parse(Console.ReadLine());
            Console.WriteLine("请输入当前的利率百分比");
            Rate = double.Parse(Console.ReadLine())/100;
            Console.WriteLine("请输入您的目标收益");
            //验证输入的有效性
            do
            {
                TargetBalance = double.Parse(Console.ReadLine());
                if (TargetBalance <= Balance) Console.WriteLine("您没有必要存钱，请重新输入一个比本金大的收益");

            } while (TargetBalance<=Balance);
            do
            {
                Balance *= (Rate+1);
                Year++;

            } while (Balance<TargetBalance);
            Console.WriteLine("您将在{0}年内，获得{1}元的收益",Year,Balance);

            Console.ReadLine();
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace _5._6_迭代语句之for循环语句
{
    class Program
    {
        static void Main(string[] args)
        {
            //求输入数的阶乘
            //1！＝1 2!=2×1 3！＝3×2×1
            //Console.WriteLine("请输入需要计算阶乘的数");
            //for(;;)
            //{ 
            //int a =int.Parse(Console.ReadLine());
            //int jc = 1;
            //for (int i=1;i<=a;i++)
            //{
            //    jc *= i;
            //}
            //Console.WriteLine("阶乘的结果是"+jc);
            Console.WriteLine("＝＝＝＝＝＝＝＝＝＝＝＝＝＝九九乘法表＝＝＝＝＝＝＝＝＝＝＝＝");
            for (int i = 1; i < 10; i++)
            {
                for (int j = 1; j <= i; j++)
                {
                    Console.Write("{0}×{1}＝{2} ", j, i, j * i);
                    if (i * j < 10) Console.Write(" ");
                }
                Console.WriteLine();
            }
            Console.ReadLine();
         
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace _5._7_迭代语句之for循环语句_2_
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("=====================九九乘法表=====================");
            //使用for循环时，一般在for循环语句进行声明循环计次的变量
            for (int i = 1; i < 10; i++)
            {

                for (int j = 1; j <= i; j++)
                {
                    Console.Write("{0}×{1}＝{2} ",j,i,j*i);
                    if (i * j < 10) Console.Write(" ");
                }
                Console.WriteLine();
            }
            Console.ReadKey();
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace _5._8_迭代语句之foreach语句
{
    class Program
    {
        static void Main(string[] args)
        {
            //for (int i = 1; i <= 50; i++)
            //{

            //    Console.WriteLine(i);
            //}

            //for (int i = 0; i < =50; i++)
            //{
            //    Console.WriteLine(i);
            //}
            //将语句识别为单词并逐行输出
            //语句用string类型  字母用char
            Console.WriteLine("请您输入一个英文句子");
            string str = Console.ReadLine();
            Console.WriteLine("您输入的句子包含以下的单词");
            foreach (char word in str)
            {
                if (char.IsWhiteSpace(word))
                {
                    Console.WriteLine();
                }
                else
                {
                    Console.Write(word);
                    //word = 't';//foreach语句的迭代变量不允许重新赋值
                }
            }

            Console.ReadKey();
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace _5._9_跳转语句之break语句
{
    class Program
    {
        static void Main(string[] args)
        {


            Console.WriteLine("输出1-500的数字，每行10个");
            for (int i = 1; i < 501; i++)
            {
                if ((i % 2 == 0) && (i % 3 == 0) && (i % 4 == 0) && (i % 5 == 0) && (i % 6 == 0) && (i % 7 == 0))
                {
                    Console.Write(i);
                    Console.WriteLine();
                    Console.WriteLine(i+"就是我们想要的那个数");
                    break;
                }

                if (i % 10 == 0) Console.WriteLine(i);
                else
                {

                    Console.Write(i+" ");
                    if (i < 10) Console.Write(" ");
                    if (i < 100) Console.Write(" ");
                }

            }
            Console.ReadLine();
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace _5._10_跳转语句之continue语句
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("50以内的奇数有：");
            for (int i = 1; i < 51; i++)
            {
                if (i % 2 == 0) continue;
                //continue语句用于停止本次迭代，并非跳出迭代语句
                Console.Write(i+"	");
            }
            Console.ReadLine();

        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace _5._11_跳转语句之return语句
{
    class Program
    {
        static void Main(string[] args)
        {
            while(true)
            {

            
            Console.WriteLine("请输入三个整数，按回车键确认每个数的输入：");
            int a = int.Parse(Console.ReadLine());
            int b = int.Parse(Console.ReadLine());
            int c = int.Parse(Console.ReadLine());
                average(a,b,c);
                //double average = (a+b+c)/3;
                //double Average = average(a,b,c);
            //Console.ReadLine();
}
        }

        static void  average(int a, int b, int c)
        {
            Console.WriteLine("您输入三个整数的平均值是：{0}", (a + b + c) / 3);

            return ;
        }      
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace _5._12_跳转语句之goto语句
{
    class Program
    {
        static void Main(string[] args)
        {
            int a = 0;
            Console.WriteLine("5的阶乘等于几？根据以下选项选择正确答案，回车键确认：");
            Console.WriteLine("1. 5!=5
2. 5!=10
3. 5!=20
4. 5!=60");
            error:
            {
                a++;
                if (a > 1) Console.WriteLine("很遗憾,您答错了,请重新输入答案.");

            }
            int option = int.Parse(Console.ReadLine());
            switch (option)
            {
                case 1:
                case 2:
                case 3: goto error;
                case 4:goto right;
                default:
                    Console.WriteLine("您选择的选项不存在");
                    goto end;

            }

            right:

            Console.WriteLine("恭喜您，答对了！");
            end:
            Console.ReadKey();

        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace _5._13_本章小结及任务实施
{
    class Program
    {
        static void Main(string[] args)
        {
            while(true)
            {
            Console.WriteLine("请输入三个整数，我们将给您算出中间数和它的阶乘");
            int a = int.Parse(Console.ReadLine());
            int b = Convert.ToInt32(Console.ReadLine());
            int c = int.Parse(Console.ReadLine());
            int middleNum = 0;
            //a是中间值，那么有两种情况，b是最小值或都b是最大值
            //b
            //c
            if (a >= b && a <= c || a >= c && a <= b)
            {
                Console.WriteLine(a + "是中间值");
                middleNum = a;

            }
            if (b >= a && b <= c || b >= c && b <= a)
            {
                Console.WriteLine(b + "是中间值");
                middleNum = b;
            }
            if (c >= a && c <= b || c >= b && c <= a)
            {
                Console.WriteLine(c + "是中间值");
                middleNum = c;
            }

            int result = 1;
            for (int i = 1; i <= middleNum; i++)
            {
                result *= i;
            }
            Console.WriteLine("它的阶乘是" + result);
        }

            Console.ReadKey();



        }
    }
}