16. Structs in C#

Level: Beginner

ℹ️ What You'll Learn

• What a struct is
• Basic difference between struct and class
• Create a simple struct
• Understand value copy behavior
• Know when beginners should use classes instead
• Use a struct for small data

A struct is a small data type you create.

It can hold multiple values together.

For beginners, remember this simple rule:

Use class for normal objects.
Use struct only for small simple values.

The Problem: Some Data is Small and Simple

Example: marks in three subjects.

English: 80
Maths: 90
Science: 85

This can be grouped into one small struct.

Quick Definitions

• Struct - Small custom data type
• Class - Main way to model real objects
• Value type - Assignment copies the value
• Reference type - Assignment copies the reference to the object
• Copy - Separate duplicate value

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Step 1: Create a Struct

public struct Marks
{
    public int English;
    public int Maths;
    public int Science;
}

Step 2: Use the Struct

Marks marks;
marks.English = 80;
marks.Maths = 90;
marks.Science = 85;

Console.WriteLine(marks.Maths);

Output:

90

Struct Copy Behavior

Struct values are copied.

Marks marks1;
marks1.English = 80;
marks1.Maths = 90;
marks1.Science = 85;

Marks marks2 = marks1;
marks2.Maths = 100;

Console.WriteLine(marks1.Maths);
Console.WriteLine(marks2.Maths);

Output:

90
100

Changing marks2 does not change marks1.

Struct vs Class

Question	Class	Struct
Best for	Real objects	Small values
Example	Student, Teacher	Marks, Point
Assignment	Copies reference	Copies value
Beginner default	Yes	No

Full Example: Marks Struct

💻 Try It — Console App

💡 Paste into Program.cs and press F5⌥ GitHub

public struct Marks
{
    public int English;
    public int Maths;
    public int Science;

    public int GetTotal()
    {
        return English + Maths + Science;
    }
}

Marks marks;
marks.English = 80;
marks.Maths = 90;
marks.Science = 85;

Console.WriteLine($"English: {marks.English}");
Console.WriteLine($"Maths: {marks.Maths}");
Console.WriteLine($"Science: {marks.Science}");
Console.WriteLine($"Total: {marks.GetTotal()}");

Expected output:

English: 80
Maths: 90
Science: 85
Total: 255

When You'll Use This in SMS

Most School Management System objects should be classes:

• Student
• Teacher
• FeeAccount
• AttendanceRecord

Structs are useful for small values:

• Marks summary
• Date range
• Simple point or coordinate

Beginner rule:

If it represents a real person or record, use class.
If it is a tiny value, struct may be okay.

Try This Now

Run the full example. Then experiment:

1. Add Social marks
2. Update GetTotal()
3. Copy marks to another variable
4. Change the copy and check the original

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ℹ️ Video Tutorial

C# structs video coming soon on NexCoding YouTube. Subscribe for updates.

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Common Mistakes

Mistake 1: Using struct for everything

Use classes for most beginner projects.

Mistake 2: Forgetting structs are copied

Changing a copied struct does not change the original.

Mistake 3: Making very large structs

Structs should be small.

Practice Task

Create a struct named FeeSummary with:

• TotalFees
• PaidAmount
• GetBalance()

Print the balance.

Quick Revision

Question	Answer
What is a struct?	Small custom data type
Beginner default?	Class
Struct assignment copies what?	Value
Good struct example?	Marks
Good class example?	Student

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🎯 Q1: What is a struct in C#?

A struct is a small custom value type.

🎯 Q2: Should beginners use class or struct more often?

Beginners should use classes more often. Use structs only for small simple values.

🎯 Q3: What happens when a struct is copied?

The value is copied. Changing the copy does not change the original.

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🤖Use AI to Learn Faster

⚠️ Important for beginners: Do NOT use AI to write your code yet. Type every example yourself. Your brain learns by doing, not by reading AI output. Use AI only to explain and quiz you — not to code for you. Once you have strong fundamentals, AI becomes a powerful productivity tool for repetitive tasks.

Use ChatGPT, Claude, or Copilot to go deeper on C# structs. Try these prompts:

• "Explain struct vs class like I am a beginner"
• "Give me 5 struct practice tasks"
• "Explain value copy behavior with simple examples"
• "Quiz me with 5 beginner questions about structs"

💡 Tip: After reading this article, paste your own code into AI and ask "What could go wrong here and why?" — fastest way to find edge cases and deepen understanding.

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