C# 数据类型 语句

一、数据类型

  基本数据类型：整型（short，long，int，byle），浮点型（float，double，decimal），bool                     

  引用类型：string，datetime，struct。。。

  类类型：object

  接口类型：interface

  数组类型：int[]..... 

 

二、运算符优先级

  算数>关系>逻辑>条件运算符>赋值

 

三、语句

  1、选择语句（if else  switch case）

     If例题：超市收银

 struct chaoshi

         {

           public double jg;

           public string name;

           public int  sl;

         }

 

        static void Main(string[] args)

        {

          ArrayList al = new ArrayList();

            chaoshi p= new chaoshi();  //初始化结构体

            

            Console.WriteLine("欢迎光临");

           while (true)

            {

                Console.Write("请输入要购买的商品名称：");

                p.name = Console.ReadLine();

                Console.Write("请输入要购买的商品数量：");

                p.sl = Convert.ToInt32(Console.ReadLine());

                Console.Write("请输入要购买的商品单价：");

                p.jg = Convert.ToDouble(Console.ReadLine());

                al.Add(p);

                Console.WriteLine("是否结账？(Y/N)");

                string sf=Console.ReadLine().ToUpper();

                if (sf=="Y")

             {  

              break;  

              }

 

              

            }

           double sum = 0;

           double sum1 = 0;

            for (int i = 0; i < al.Count; i++)

   {

                   chaoshi x = (chaoshi)al[i];

                   sum += x.jg * x.sl;

                   

   }

            if (sum<100)

            {

                sum1 = 0.95 * sum;

            }

            else if (sum<200)

            {

                sum1= 0.90 * sum;

            }

            else if (sum < 300)

            {

                sum1 = 0.80 * sum;

            }

            else if (sum < 500)

            {

                sum1 = 0.70 * sum; 

            }

            else

            {

                sum1 = 0.60 * sum; 

            }

            Console.WriteLine("花费"+sum1+"元，节省"+(sum-sum1)+"元");

            Console.ReadLine();

          }

 

   

Switch例题：输入月份 几号，判断第几天

 

          Console.Write("请输入月份");

            int y = int.Parse(Console.ReadLine());

            Console.Write("请输入日期");

            int d = int.Parse(Console.ReadLine());

            int m1 = 31, m2 = 28, m3 = 31, m4 = 30, m5 = 31, m6 = 30, m7 = 31, m8 = 31, m9 = 30, m10 = 31, m11 = 30;

            switch (m)

            {

                case 1:

                    Console.WriteLine("第" + d.ToString() + "天");

                    break;

                case 2:

                    Console.WriteLine("第" + (m1 + d).ToString() + "天");

                    break;

                case 3:

                    Console.WriteLine("第" + (m1 + m2 + d).ToString() + "天");

                    break;

                case 4:

                    Console.WriteLine("第" + (m1 + m2 + m3 + d).ToString() + "天");

                    break;

                case 5:

                    Console.WriteLine("第" + (m1 + m2 + m3 + m4 + d).ToString() + "天");

                    break;

                case 6:

                    Console.WriteLine("第" + (m1 + m2 + m3 + m4 + m5 + d).ToString() + "天");

                    break;

                case 7:

                    Console.WriteLine("第" + (m1 + m2 + m3 + m4 + m5 + m6 + d).ToString() + "天");

                    break;

                case 8:

                    Console.WriteLine("第" + (m1 + m2 + m3 + m4 + m5 + m6 + m7 + d).ToString() + "天");

                    break;

                case 9:

                    Console.WriteLine("第" + (m1 + m2 + m3 + m4 + m5 + m6 + m7 + m8 + d).ToString() + "天");

                    break;

                case 10:

                    Console.WriteLine("第" + (m1 + m2 + m3 + m4 + m5 + m6 + m7 + m8 + m9 + d).ToString() + "天");

                    break;

                case 11:

                    Console.WriteLine("第" + (m1 + m2 + m3 + m4 + m5 + m6 + m7 + m8 + m9 + m10 + d).ToString() + "天");

                    break;

                case 12:

                    Console.WriteLine("第" + (m1 + m2 + m3 + m4 + m5 + m6 + m7 + m8 + m9 + m10 + m11 + d).ToString() + "天");

                    break;

                default:

                    Console.WriteLine("您输入有误");

                    break;

            }            

    2、  循环语句（for， foreach，while）    

      例题：冒泡排序

  

            for (int i =0; i <x; i++)

            {

                for (int j = i; j < x-1; j++)

                {

                    if (px[j-1]<px[i])

                    {

                        int temp = 0;

                        temp = px[j-1];

                        px[j-1] = px[ i ];

                        px[ i ] = temp;

                    }

                }

            }

3、跳转语句：break（跳出整个循环），continue（跳出当前循环），default，return

    break与continue的区别：

  
        static void Main(string[] args)
        {

            int n = 0;
            while (n < 100)
            {
                n++;
                Console.WriteLine(n + "口饭");
                if (n == 50)
                {
                    Console.WriteLine("出现了一块石头，我吐了。");
                    continue;

                }
                if (n == 80)
                {
                    Console.WriteLine(n + "出现了一只虫子。我。。。。喊老板了。。。。");
                    break;
                }

                Console.WriteLine("我咽了下去");

            }

}

4 、异常语句：try-catch-finally