C#编写一个函数来计算以对象数组为参数的平均年龄

Question

我必须创建一个函数来计算一个班级 50 名学生的平均年龄，这是我的代码

        public class Student
        {
        public int[] age = new int[10];
        Student()
        {
            age[0] = 17;
            age[1] = 19;
            age[2] = 17;
            age[3] = 18;
            age[4] = 17;
            age[5] = 18;
            age[6] = 18;
            age[7] = 19;
            age[8] = 17;
            age[9] = 18;
        }

    }
    class Program
    {
        public void averageAge(Student student)
        {
            foreach(int i in student.age)
            {
                int avgage = (i += i) / 2;
            }
        }
        static void main (string[] args)
        {
          
        }

我得到一个错误，说不能分配给“i”它是一个 foreach 迭代变量，任何其他方式我都可以为学生年龄初始化这个数组，因为我必须计算 50 名学生的平均年龄，所以分配 50 个不同的时间感觉有点多余

我不知道以这种方式使用 foreach 时我在想什么，我现在用 for 循环交换了 foreach，如下所示：

public void averageAge(Student student)
        {
            int avgage = 0;
            for (int i =0;i<50;i++)
            {
               avgage += student.age[i];
            }
            avgage /= 50;
        }

Answer 1

使用 Linq 你可以写：

using System.Linq;

var student = new Student();

int averageAge = (int)student.age.Average();

https://docs.microsoft.com/dotnet/api/system.linq.enumerable.average

否则你可以编写这个循环：

int averageAge = 0;

for ( int index = 0; index < student.age.Length; index++ )
  averageAge = ( averageAge + student.age[index] ) / 2;

Console.WriteLine(avgage);

一个foreach是：

foreach ( int value in student.age )
  averageAge = ( averageAge + value ) / 2;

因此方法可以是：

public int GetAverageAge(Student student)
{
  int result = 0;
    foreach ( int value in student.age )
      result = ( result + value ) / 2;
  return result;
}

你这样使用：

static void main (string[] args)
{
  var student = new Student();
  int averageAge = GetAverageAge(student);
}

输出：

Linq = 17
Loop = 17

将构造函数公开，您可以将方法放在类本身中：

public class Student
{
  public int[] age = new int[10];

  public int GetAverageAge()
  {
    int result = 0;
    foreach ( int value in student.age )
      averageAge = ( averageAge + value ) / 2;
    return result;
  }

  public Student()
  {
    ...
  }
}

你也可以使用属性：

public int AverageAge
{
  get
  {
    int result = 0;
    foreach ( int value in student.age )
      averageAge = ( averageAge + value ) / 2;
    return result;
  }
}

或者简单地说：

public int AverageAge => (int)age.Average();

每个班级的实例是针对一个学生的多个年龄还是一个学生班级？

Answer 2

不是答案，但我认为这就是您想要实现的目标。它可能对您的思考过程有所帮助

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

public class Program
{
    public static void Main()
    {
        // create a classroom
        var classRoom = new ClassRoom();
        // store 10 students in classroom, aged between 18 and 30 (random)
        for (int i = 0; i < 10; i++)
        {
            classRoom.Students.Add(new Student(new Random().Next(18, 30)));
        }

        // calculate average age of students in a classroom
        // this can be done a hundred ways. Linq is probably shortest
        Console.WriteLine($"There are {classRoom.Students.Count} students with an average age of { classRoom.Students.Average(s => s.Age)}");
        Console.ReadKey();
    }

    // a student has an age
    class Student
    {
        public Student(int age)
        {
            Age = age;
        }

        public int Age { get; set; }
    }

    // a class has a number of students
    class ClassRoom
    {
        public List<Student> Students { get; } = new List<Student>();
    }
}