C set

aggregate （Collection） Class is a class designed for data storage and Retrieval . These classes provide a pair of stacks （stack）、 queue （queue）、 list （list） Hash table （hash table） Support for . Most collection classes implement the same interface .

aggregate （Collection） Classes serve different purposes , Such as dynamically allocating memory for elements , Index based access to list items, etc . These classes create Object A collection of objects of a class . stay C# in ,Object Class is the base class for all data types .

1. There is a known Worker Under the class ：

public class Worker

{

    private int age;

    private string name;

    private double salary;
    public Worker ()
    {

    }
    public Worker (String name, int age, double salary)
    {

        this.name = name; 
        this.age = age;
        this.salary = salary;

    }

    public void work(){
    
        Console.WriteLine(" full name ：" + name + "  Age ：" + age + "  Wages ：" + salary + " work");
    
        }
}

Complete the following requirements

1. Create a List, stay List Add three workers to the , The basic information is as follows ：

full name      Age     Wages

zhang3   18      300    

li4      25      3500 

wang5    22      3200

1. stay li4 Insert a worker before , The message is ： full name ：zhao6, Age ：24, Wages 3300
2. Delete wang5 Information about
3. utilize for Loop traversal , Print List Information about all workers in the

        static void Main(string[] args)
        {
            //1.
            // Complete the following requirements 
            //1)  Create a  List, stay  List  Add three workers to the , The basic information is as follows ：
            // full name   Age    Wages 
            //zhang3  18  300
            //li4 25  3500
            //wang5   22  3200

            List<Worker> list = new List<Worker>();
            Worker w1 = new Worker("zhang3", 18, 300);
            Worker w2 = new Worker("li4", 25, 3500);
            Worker w3 = new Worker("wang5", 22, 3200);
            list.Add(w1);
            list.Add(w2);
            list.Add(w3);
            //2)	 stay  li4  Insert a worker before , The message is ： full name ：zhao6, Age ：24, Wages  3300
            list.Insert(1, new Worker("zhao6", 24, 3300));
            //3)	 Delete  wang5  Information about 
            list.RemoveAt(3);
            //4)	 utilize  for  Loop traversal , Print  List  Information about all workers in the 
            for (int i = 0; i < list.Count; i++)
            {
                list[i].work();
            }
        }

            3. There are the following List
            List<Student> list = new List<Student>();
            list.add(new Student(“Tom”, 18, 100, “class05”));
            list.add(new Student(“Jerry”, 22, 70, “class04”));
            list.add(new Student(“Owen”, 25, 90, “class05”));
            list.add(new Student(“Jim”, 30, 80, “class05”));
            list.add(new Student(“Steve”, 28, 66, “class06”));
            list.add(new Student(“Kevin”, 24, 100, “class04”));
            In this list On the basis of , Complete the following requirements ：
            1） Calculate the average age of all students

            2） Calculate the average score of each class

    class Student
    {
        public  string name;
        public  int age;
        public  double score;
        public  string classNum;// Class number  

        public Student(string v1, int v2, int v3, string v4)
        {
            this.name = v1;
            this.age = v2;
            this.score = v3;
            this.classNum  = v4;
        }
    }
        static void Main(string[] args)
        {
            //1）  Calculate the average age of all students 
            List<Student> list2 = new List<Student>();
            list2.Add(new Student("Tom", 18, 100, "class05"));
            list2.Add(new Student("Jerry", 22, 70, "class04"));
            list2.Add(new Student("Owen", 25, 90, "class05"));
            list2.Add(new Student("Jim", 30, 80, "class05"));
            list2.Add(new Student("Steve", 28, 66, "class06"));
            list2.Add(new Student("Kevin", 24, 100, "class04"));
            int sum = 0;
            for (int i = 0; i < list2.Count; i++)
            {
                 sum+= list2[i].age;
            }
            Console.WriteLine(" Average age ："+sum/list2.Count);
            //2）  Calculate the average score of each class 
            int a = 0;
            double sum1 = 0;
            int b = 0;
            double  sum2 = 0;
            int c = 0;
            double sum3 = 0; 
            for (int i = 0; i < list2.Count; i++)
            {
                if (list2[i].classNum =="class05")
                {
                    sum1 += list2[i].score;
                    a++;
                }
                else if(list2[i].classNum == "class04")
                {
                    sum2 += list2[i].score;
                    b++;
                }
                else if (list2[i].classNum == "class06")
                {
                    sum3 += list2[i].score;
                    c++;
                }

            }
            Console.WriteLine("class04 Class average ："+sum1/a);
            Console.WriteLine("class05 Class average ："+sum2/b);
            Console.WriteLine("class06 Class average ："+sum3/c);
        }