C++ Class vs Struct: Key Differences Explained
In C++, a class defaults members to private and a struct defaults them to public; otherwise they are identical.
Many tutorials say “struct is for plain data, class is for objects.” That half-truth sticks, so teams often pick struct when they need simple POD and class when they want methods and inheritance, even though the compiler treats them the same.
Key Differences
1. Default visibility: class = private, struct = public.
2. Default inheritance: class = private, struct = public.
3. Otherwise identical—templates, virtual functions, operators, and layout work the same.
Which One Should You Choose?
Use struct for passive data bundles and POD types; use class for encapsulation and polymorphism. Pick one style per codebase and stay consistent to avoid surprises.
Examples and Daily Life
struct Pixel { int r, g, b; }; // Plain RGB
class Window { public: void show(); private: int handle; }; // Encapsulated behavior.
Can a struct have constructors and virtual functions?
Yes—syntax and behavior are the same as in a class.
Is sizeof(struct) always equal to sizeof(class)?
Yes, given the same data layout; visibility and keyword don’t change size.