Struct vs Class

tldr. both are almost similar with default visibility of data and functions being public in Struct and private in Class.

key differences:

1. Default Access Specifier:

   • In a class, members are private by default.

   • In a struct, members are public by default.

2. Inheritance:

   • For a class, the default inheritance is private.

   • For a struct, the default inheritance is public.

3. Purpose and Convention:

   • Classes are typically used for objects with both data and methods, often implementing data hiding.

   • Structs are conventionally used for passive objects with public data and few or no methods.

4. Functionality:

   • Functionally, classes and structs are almost identical in C++.

   • You can add methods, constructors, and use inheritance with both.

Here's a brief example to illustrate these differences:

struct MyStruct {
    int x;  // public by default
    void print() { std::cout << x << std::endl; }
};

class MyClass {
    int x;  // private by default
public:
    void print() { std::cout << x << std::endl; }
};

int main() {
    MyStruct s;
    s.x = 5;  // OK, x is public

    MyClass c;
    // c.x = 5;  // Error, x is private
    
    return 0;
}

In this example:

• The struct's member x is accessible directly.

• The class's member x is private and not accessible outside the class.

Inheritance example:

struct BaseStruct {};
struct DerivedStruct : BaseStruct {};  // public inheritance by default

class BaseClass {};
class DerivedClass : BaseClass {};  // private inheritance by default

It's worth noting that in practice, the choice between struct and class often comes down to coding style and convention rather than functionality. Many C++ programmers use structs for simple data structures and classes for more complex objects with behavior.