结构体

结构体：
在内存中临时存储数据的方式
1、变量、常量
2、数组，可以存储固定长度统一类型的数据
3、集合
4、结构体

学生信息：姓名，性别，年龄，系别

结构体含义：就是将生活中的一些个体，封装成一个特殊的类型

结构体是：用户自定义数据类型

创建：
创建的位置：main函数之外
struct Student
{
    public int Code;
    public string Name;
    public string Sex;
    public int Old;
    public DateTime Birthday;
}

定义：声明
Student s = new Student(); //实例化

赋值：
s.Code = 1;
s.Name = "张三";
s.Sex = "男";
s.Old = 18;
s.Birthday = Convert.ToDateTime("1999-1-1");

取值：
s.Code //放在等号左边就是给它赋值，放在右边就是使用它的值

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

namespace 结构体
{
    class Program
    {
        struct student 
        {
            public string name;
            public string sex;
            public int old;
            public decimal grade;
  
        }
        
        static void Main(string[] args)
        {
            Console.Write("请输入学生的个数：");
            int a =Convert.ToInt32(Console.ReadLine());
            student s = new student();
            ArrayList arr = new ArrayList();
            for (int i = 0; i < a; i++)
            {

                Console.Write("请输入第" + (i + 1) + "个学生的姓名：");
                s.name = Console.ReadLine();
                while (true)
                {
                    if (s.name == " ")
                    {
                        Console.Write("请输入第" +( i + 1) + "个学生的姓名：");
                        s.name = Console.ReadLine();
                    }
                    else if (s.name != " ")
                    {
                        break;
                    }
                }
                while (true)
                {
                    Console.Write("请输入第" + (i + 1) + "个学生的性别：");
                    s.sex = Console.ReadLine();
                    if (s.sex == "男" || s.sex == "女")
                    {
                        break;
                    }
                }
                while (true)
                {
                    try
                    {
                        Console.Write("请输入第" +( i + 1) + "个学生的年龄：");
                        s.old = Convert.ToInt32(Console.ReadLine());
                        break;
                    }
                    catch
                    {
                    }
                }
                while (true) 
                {
                    try
                    {
                        Console.Write("请输入第" + (i + 1) + "个学生的成绩：");
                        s.grade = Convert.ToInt32(Console.ReadLine());
                        break;
                    }
                    catch
                    {
                    }
                }
                arr.Add(s);
            }
            decimal sum = 0;
            //student ss = (student)arr[i];
            for (int i = 0; i < arr.Count; i++) 
            {
                student so = (student)arr[i];
                //Console.WriteLine("第" + (i + 1) + "个学生的姓名是："+ss.name + "，性别是：" + ss.sex + "，年龄是：" + ss.old + "，成绩是：" + ss.grade+"。");
                sum += so.grade;
                
            }


            Console.WriteLine("总分是：" + sum + ",平均分是：" + (sum / a) + "。");

            //student ss = (student)arr[i];
            //student sss = (student)arr[j];
            for (int i = 0; i < arr.Count; i++) 
            {
                for (int j= i+1; j < arr.Count; j++)
                {
                    student ss = (student)arr[i];
                    student sss = (student)arr[j];
                    if (ss.old < sss.old) 
                    {
                        object zhong=arr[i];
                        arr[i]=arr[j];
                        arr[j] = zhong;

                    }                
                }
            
            }
            foreach (student x in arr)
            {
                
                Console.WriteLine("姓名是：" + x.name + "，性别是：" + x.sex + "，年龄是：" + x.old + "，成绩是：" + x.grade + "。");
            }
            for (int i = 0; i < arr.Count; i++)
            {
                for (int j = i + 1; j < arr.Count; j++)
                {
                    student ss = (student)arr[i];
                    student sss = (student)arr[j];
                    if (ss.grade < sss.grade)
                    {
                        object zhong = arr[i];
                        arr[i] = arr[j];
                        arr[j] = zhong;

                    }
                }

            }
            foreach (student x in arr)
            {

                Console.WriteLine("姓名是：" + x.name + "，性别是：" + x.sex + "，年龄是：" + x.old + "，成绩是：" + x.grade + "。");
            }

                Console.ReadLine();
        }
    }
}