Switch

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

namespace _180821汪敏
{
    class Program
    {
        static void Main(string[] args)
        {
           /* double a, b, c, t;
            Console.WriteLine("请输入a,b,c的值");
                a = Convert.ToDouble(Console.ReadLine());
                b = Convert.ToDouble(Console.ReadLine());
                c = Convert.ToDouble(Console.ReadLine());
                if (a > b)
                {
                    t = a;
                    a = b;
                    b = t;
                }
                if (a > c)
                {
                    t = a;
                    a = c;
                    t = c;
                }
                if (b > c)
                {
                    t = b;
                    b = c;
                    c = t;
                }
                Console.WriteLine("三个数的升序是："+a+","+b+","+c);*/
                double score;
                Console.WriteLine("请输入学生成绩");
                score = Convert.ToDouble(Console.ReadLine());
                if(score<0||score>100)
                Console.WriteLine("成绩不合理");
                else
                    /*if (score > 90)
                    Console.WriteLine("优");
                else
                if (score>80)
                    Console.WriteLine("良");
                else 
                if (score >60)
                    Console.WriteLine("中等");
                else
                    Console.WriteLine("差");*/
                    switch((int)(score / 10))
                    {
                        case 10:
                        case 9:Console.WriteLine("优");break;
                        case 8: Console.WriteLine("良"); break;
                        case 7: 
                        case 6:Console.WriteLine("中");break;
                        default: Console.WriteLine("差"); break;
                    }

                double x,y;char  z;
                Console.WriteLine("请输入两个数");
                x = Convert.ToDouble(Console.ReadLine());
                y = Convert.ToDouble(Console.ReadLine());
                Console.WriteLine("请输入运算符号");
                z = Convert.ToChar(Console.ReadLine());
            switch(z){
                case '+': Console.WriteLine(x + "" + z + "" + y + "=" + (x + y)); break;
                case '-': Console.WriteLine(x + "" + z + "" + y + "=" + (x - y)); break;
                case '*': Console.WriteLine(x + "" + z + "" + y + "=" + (x * y)); break;
                case '/': Console.WriteLine(x + "" + z + "" + y + "=" + (x / y)); break;
            }


        }
    }
}