Difference between a struct and a class in dotnet framework

In the .NET Framework, both struct and class are used to define types, but they have key differences in behavior, performance, and usage. Here's a breakdown:

 1. Value Type vs. Reference Type

• Struct: Value type

  • Stored on the stack (or inline in memory).

  • Copied by value when assigned or passed to methods.

• Class: Reference type

  • Stored on the heap.

  • Copied by reference, meaning multiple variables can point to the same object.

2. Memory Allocation

• Structs are lightweight and allocated on the stack (when not boxed), making them faster for small data structures.

• Classes are allocated on the heap and involve garbage collection.

3. Inheritance

• Struct:

  • Cannot inherit from another struct or class.

  • Can implement interfaces.

• Class:

  • Can inherit from another class (single inheritance).

  • Can also implement interfaces.

4. Default Constructor

• Struct:

  • Cannot define a parameterless constructor (in .NET Framework; .NET Core 2.1+ allows it with readonly struct).

  • Always has an implicit parameterless constructor that initializes fields to default values.

• Class:

  • Can define parameterless and parameterized constructors freely.

5. Mutability

• Structs are best kept immutable (like numbers or DateTime) to avoid bugs with value copying.

• Classes can be mutable or immutable.

6. Use Cases

Use struct for:

• Small, simple types.

• Short-lived objects.

• Types that represent single values (like Point, Color, DateTime).

Use class for:

• Complex behavior.

• Objects that are large or frequently modified.

• Need for polymorphism (inheritance and virtual methods).

In the C# the structs and classes both are used to define types, struct defines value type and class define reference type. 
We use struct where we don't need inheritance and performance matters for small, simple types. 
We use class when we need reference semantics, polymorphism, or to represent complex entities.