Defining & Using a Structure

We define a structure using the following syntax:

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struct structureName
{
    public datatype fieldName1;
    public datatype fieldName2;
    public datatype fieldName3;
    ...
}

For-example we can define a structure for storing some student data:

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struct Student
{
    public int id;
    public float age;
    public string name;
    public string course;
    public char grade;
}

Now for storing data we need to create an instance (also called an object) using this structure. A structure is basically a custom datatype, and hence it can be treated as such. So for creating a new object of the structure, we simply use the following syntax:

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              1
            
structName variableName;

We can create multiple objects of the Student class, all of which can store data:

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              123
            
Student student1;
Student student2;
Student student3;

Each object we created has the set of fields defined in the Student structure and we can store and access data from those fields using the variableName.fieldName syntax. For example we can access and output the name field of student2:

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              1
            
Console.WriteLine(student2.name);

When an empty object is created, the fields take up zero values depending upon their datatypes:

string - empty string "";
char - empty character '';
int - 0;
float - 0.0;
bool - false.

Therefore, the student2.name will give an empty output.

We can store data in it using the assignment operator (=):

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              1
            
student2.name = "Alex";

This way we can store data in all of the three objects:

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using System;

struct Student
{
    public int id;
    public float age;
    public string name;
    public string course;
    public char grade;
}
class ConsoleApp
{
    static void Main(string[] args)
    {
        Student student1;
        student1.id = 1;
        student1.name = "Abigail";
        student1.age = 21;
        student1.course = "C#";
        student1.grade = 'A';
        Console.WriteLine($"{student1.name} is {student1.age} years old.");

        Student student2;
        student2.id = 2;
        student2.name = "Alex";
        student2.age = 22;
        student2.course = "C#";
        student2.grade = 'B';
        Console.WriteLine($"{student2.name} has a {student2.grade} in {student2.course}.");

        Student student3;
        student3.id = 3;
        student3.name = "Jennifer";
        student3.age = 19;
        student3.course = "C#";
        student3.grade = 'A';
        Console.WriteLine($"{student3.name} studies {student3.course}.");
    }
}

1. Which keyword is used for defining a structure?

2. What is the output of the following code?

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