Why should I even consider using structs in C++?

Question

Is there ever an advantage of declaring a struct in C++? Why shouldn't I just make a class consisting only of data members(i.e. no methods)?

Thanks,

There's no such thing as "a struct" in C++. There's the `struct` keyword, but it's used to declare a *class*. — Kerrek SB, Oct 07 '16 at 21:35
@KerrekSB That's what I was unaware of. Is using the 'struct' keyword simply an alternative way to define a class consisting only of data members? — Izzo, Oct 07 '16 at 21:38
Not even. It's "simply an alternative way to define a class", period. — Kerrek SB, Oct 07 '16 at 21:38
The only difference is that the default access policy is public instead of private. — David, Oct 07 '16 at 21:39
Documentation. Many people use `struct` when creating plain aggregate data and `class` when defining business objects and data abstractions etc. — Galik, Oct 07 '16 at 21:45
The standard does talk about a `POD struct`, but it is still just a class. — wally, Oct 07 '16 at 21:48
I'd say the main reason it is a keyword in C++ is for backwards compatibility with C. — QuarterlyQuotaOfQuotes, Oct 07 '16 at 22:43
Instead of complaining, edit your question to be better. So long as exiting answers remain valid this is ideal. — Yakk - Adam Nevraumont, Oct 07 '16 at 22:54

score 5 · Accepted Answer · answered Oct 07 '16 at 21:38

When you have a POD type where everything is public is saves a line...

struct Color {
    int r;
    int g;
    int b;
};

vs

class Color {
public:
    int r;
    int g;
    int b;
};

And it's also common practice for objects which are just dumb containers of things. Dumb meaning no constructors, operators, methods.

score 4 · Answer 2 · answered Oct 07 '16 at 21:43

My favorite reason is inheritance. consider this code:

class MyClass : public Base1, public virtual Base2 {
public:
    void fun1() override;

private:
    int m1;
};

Now consider this very example with a struct:

struct MyClass : Base1, virtual Base2 {
    void fun1() override;

private:
    int m1;
};

Some say C++ is too verbose, but when checking their code, it look much more like the first example. I find struct much easier to read than class. In my project I use struct everywhere.

The question you should ask is "Why should I even consider using classes in C++?", because IMO, struct are the same but less verbose.

Why should I even consider using structs in C++?

2 Answers2

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