我的.Net学习第三天

续C#基础知识：

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

namespace  switch运算
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("请输入成绩");
            string strScore = Console.ReadLine();
            string result = null;
            switch(strScore)
            {
                case "60":
                    result = "及格";
                    break;
                case "70":
                    result = "中等";
                    break;
                case "80":
                    result = "良好";
                    break;
                case "90":
                    result = "优秀";
                    break;
                default:
                    result = "不及格";
                    break;
            }
            Console.WriteLine("{0}",result);
            Console.ReadKey();
        }
    }
}

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

namespace 登陆验证
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("请输入用户名");
            string userName = Console.ReadLine();
            Console.WriteLine("请输入密码");
            string pwd = Console.ReadLine();

            if (userName == "admin" && pwd == "1234")
            {
                Console.WriteLine("欢迎您登录！");
            }
            else
            {
                Console.WriteLine("用户名或密码错误！");
            }

            Console.ReadKey();
        }
    }

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

namespace 比较求较大的数
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("请输入数字1");
            string data1 = Console.ReadLine();
            Console.WriteLine("请输入数字2");
            string data2 = Console.ReadLine();
            int i1 = 0, i2 = 0;
            string result=null;
            //判断输入的数字格式是否正确
            if (int.TryParse(data1, out i1) == false || int.TryParse(data2, out i2) == false)
            {
                Console.WriteLine("请输入正确格式的数字");
            }
            else
            {
                switch (i1 / i2)
                {
                    case 0:
                        result = i2.ToString();
                        break;
                    default:
                        result = i1.ToString();
                        break;
                }
                Console.WriteLine("输入的数字是 {0} 和 {1} ,较大的数是 {2}", data1, data2, result);
            }
            Console.ReadKey(); 
        }
    }
}

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

namespace 成绩考核
{
    class Program
    {
        static void Main(string[] args)
        {
            //输入成绩
            Console.WriteLine("请输入成绩");
            string score = Console.ReadLine();
            //转换为整数
            string result = null;
            int data =0;
            if (int.TryParse(score, out data) == false)
            {
                Console.WriteLine("请输入整数");
            }
            else
            {
                //取十位数
                data = data / 10;
                if ((data) >= 9)
                {
                    result = "优秀";
                }
                else if (8 <= data)
                {
                    result = "良好";
                }
                else if (7 <= data)
                {
                    result = "中等";
                }
                else if (6 <= data)
                {
                    result = "及格";
                }
                else
                {
                    result = "不及格";
                }
                Console.WriteLine("成绩考核结论为 {0}", result);
            }
            Console.ReadKey();

        }
    }
}

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

namespace 四则运算
{
    class Program
    {
        static void Main(string[] args)
        {
            //输入两个数字，输入操作符，输出计算结果
            Console.WriteLine("请输入第一个数字");
            string strData1 = Console.ReadLine();
            Console.WriteLine("请输入第二个数字");
            string strData2 = Console.ReadLine();
            Console.WriteLine("请输入操作符 + - * /");
            string operation = Console.ReadLine();
            //检查数字是否合法
            int data1 = 0, data2 = 0;
            float result = 0;
            if (int.TryParse(strData1, out data1) == false || int.TryParse(strData2, out data2) == false)
            {
                Console.WriteLine("请输入整数");
            }
            else if (operation != "+" && operation != "-" && operation != "*" && operation != "/")
            {
                Console.WriteLine("操作符错误，只接受 + - * /");
            }
                //如果是除法，检查除数是否为0
            else if (operation == "/" && data2 == 0)
            {
                Console.WriteLine("除数不能为0");
            }
            else
            {
                switch (operation)
                {
                    case "+":
                        result = data1 + data2;
                        break;
                    case "-":
                        result = data1 - data2;
                        break;
                    case "*":
                        result = data1 * data2;
                        break;
                    case "/":
                        result = (float)data1 / data2;
                        break;
                }
                Console.WriteLine("计算结果为：{0}", result);
            }
            Console.ReadKey();


        }
    }
}