When to Use Classes and Structures in C++

1. Default Access Control:

• struct's members and inheritance default to public.
• class's members and inheritance default to private.

1. Usage Scenarios:

• struct: Typically used for defining pure data structures with minimal methods and simple logic. It is primarily for data storage and straightforward data processing, suitable for scenarios where data needs to be packaged, such as defining protocol data packets or representing simple data records.
• class: Suitable for complex object models requiring encapsulation, inheritance, and polymorphism. Classes provide enhanced capabilities, including private member declaration, separation of interface and implementation, and support for inheritance and polymorphism, making them ideal for building complex systems.

1. Selection Recommendations:

• If data members can be accessed freely and you only need a simple data container, using struct is more appropriate.
• If you require encapsulation, controlled data access, or object-oriented features like inheritance and polymorphism, you should use class.

Overall, choosing between struct and class primarily depends on whether your requirements demand complex functionality and access control. In practical development, the distinction between them may not be rigid, and the choice is often based on the team's programming style and conventions.