Structs

📌 1. What is a Struct?

• A struct is a value type in C#.

• Unlike classes, which are reference types (live on the heap), structs are usually stored on the stack and are copied by value.

• Structs are typically used for small, lightweight objects that represent a single value or a group of related values.

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📌 2. Syntax Example

public struct Point
{
    public int X;
    public int Y;
 
    // Constructor
    public Point(int x, int y)
    {
        X = x;
        Y = y;
    }
 
    // Method
    public void Display()
    {
        Console.WriteLine($"Point({X}, {Y})");
    }
}
 
class Program
{
    static void Main()
    {
        Point p1 = new Point(3, 4);
        p1.Display();
 
        // Copying by value
        Point p2 = p1;
        p2.X = 10;
        p1.Display(); // still (3,4)
        p2.Display(); // (10,4)
    }
}

Output:

Point(3, 4)
Point(3, 4)
Point(10, 4)

• Notice how changing p2 doesn’t affect p1 — because structs are copied by value.

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📌 3. Key Differences Between Structs and Classes

Feature	Struct	Class
Type	Value type	Reference type
Memory	Stack (usually)	Heap
Copying	By value (copy)	By reference (pointer)
Inheritance	Cannot inherit from another struct	Can inherit
Default Constructor	Automatically provided	Can define explicitly
Ideal for	Small, immutable data	Large, complex objects

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📌 4. When to Use Structs

• Represent small, simple data structures: points, coordinates, RGB colors, etc.

• Performance-critical code where heap allocation is expensive.

• When you want value semantics (copy by value instead of reference).

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📌 5. Notes

• Structs can have methods, properties, and constructors (but no parameterless constructor in older versions of C#).

• Avoid large structs — copying big structs can hurt performance.

• Structs cannot inherit from other structs or classes (but they can implement interfaces).

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✅ In short:
Structs are value types, lightweight alternatives to classes, and are copied by value rather than by reference. They are part of C#’s type system, just like classes, enums, tuples, and so on.