Structs with Other Data Structures

Since structs are essentially data types, we can use them for creating Arrays and Lists as well:

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using System;
using System.Collections.Generic;

struct Student
{
    public string name;
    public int age;
}

class Program
{
    static void Main()
    {
        // An array of 50 students
        Student[] studentsArr = new Student[50];

        // A list of students
        List<Student> studentsList;
    }
}

In a List or an Array, we would access a Student object's field using the following syntax:

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              1
            
variableName[index].fieldName

For-example:

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              1234567
            
// Array
studentsArr[17].name = "Alex";

// List
studentsList[27].age = 21;

// Note: Both have the same syntax.

We can also loop through these arrays or lists to assign or access data. For-example the following code loops through a List of Students objects and calculates the average age:

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using System;
using System.Collections.Generic;

struct Student
{
    public string name;
    public int age;
}

class Program
{
    static void Main()
    {
        // Creating an array
        Student[] students = new Student[7];

        // Setting some data
        students[0].age = 18;
        students[1].age = 13;
        students[2].age = 16;
        students[3].age = 21;
        students[4].age = 30;
        students[5].age = 36;
        students[6].age = 20;

        int totalAge = 0;
        for (int i = 0; i < students.Length; i++)
        {
            totalAge += students[i].age;
        }

        // Formula for average is "sum of elements / number of elements"
        float averageAge = totalAge / students.Length;

        Console.WriteLine($"Average Age: {averageAge}");
    }
}

It is clear that here the Student struct acts like a data type. We can also use Student as a dictionary value as well. Following is an example of using Struct as a value in a dictionary:

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using System;
using System.Collections.Generic;

struct Student
{
    public string name;
    public int age;
}

class Program
{
    static void Main()
    {
        var studentsByID = new Dictionary<int, Student>();

        Student student;
        student.name = "Thomas";
        student.age = 36;

        studentsByID.Add(0, student);

        Console.WriteLine(studentsByID[0].name);
    }
}

Everything was clear?

Section 2. Chapter 4