Why I can't define a static field in the declaration?

Question

So it looks like I can't do this for some reason...

class MyClass
{
    static std::string name = "Whatever";
};

I don't get it, for me it would make sense to define something in the declaration, even if is static, but instead, I have to do this... ¿?¿?¿?

class MyClass
{
    static std::string name;
};
std::string MyClass::name = "Whatever";

And by the way... Isn't name private by default? Then why can I change its value from outside the class?

@scohe001 No, the rules are stricter for `std::string` than for `int`. Much of that page does not apply. — Asteroids With Wings, Oct 29 '20 at 13:04
@Asteroids would you prefer [Static constant string (class member)](https://stackoverflow.com/q/1563897/2602718) then? — scohe001, Oct 29 '20 at 13:06

score 4 · Accepted Answer · answered Oct 29 '20 at 13:03

4

Why I can't define a static field in the declaration?

You can!

#include <string>

class MyClass
{
    static inline std::string name = "Whatever";
    //     ^^^^^^
};

Isn't name private by default? Then why can I change its value from outside the class?

You can't!

You're defining/initialising it, not changing its value.

answered Oct 29 '20 at 13:03

Asteroids With Wings

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No I can't, It says "a nonstatic data member cannot be declared as inline" – Karlos Oct 29 '20 at 13:06
@Karlos Then your compiler is ancient, or set in ancient mode. What is it and what standard are you using? – Asteroids With Wings Oct 29 '20 at 13:07
[Live demo of it working](https://coliru.stacked-crooked.com/a/da979b9296288857) – Asteroids With Wings Oct 29 '20 at 13:08
I am using Visual Studio 2019 – Karlos Oct 29 '20 at 13:08
Hang on... "nonstatic"?? – Asteroids With Wings Oct 29 '20 at 13:08
yep, thats what is says, i dont know what it means though im just coming from c# – Karlos Oct 29 '20 at 13:08
@Karlos Did you remove the `static` keyword by mistake? – Asteroids With Wings Oct 29 '20 at 13:09
nope, that joint is still there – Karlos Oct 29 '20 at 13:10
That makes no sense. – Asteroids With Wings Oct 29 '20 at 13:10
i know, that's why im asking – Karlos Oct 29 '20 at 13:11
I have no answer for that. That cannot happen. The compiler doesn't complain about "nonstatic" members when they're static, and VS 2019 supports inline there. – Asteroids With Wings Oct 29 '20 at 13:11
well, that's why i got written here, thx for answering though, idk, it's static, but then it's telling me that is nonstatic... – Karlos Oct 29 '20 at 13:13
Are you sure you're rebuilding the right file? – Asteroids With Wings Oct 29 '20 at 13:17
You need to add "/std:c++17" switch (not sure about GUI) for `inline` to work on MSVC. – sklott Oct 29 '20 at 13:26
Yes @AsteroidsWithWings, It's an empty proyect, im just seeing how classes work in c++ compared to c#. – Karlos Oct 29 '20 at 13:37
@sklott where ? – Karlos Oct 29 '20 at 13:38
In case anyone is wondering, the Intellisense in VS 2019 (and VS 2022 for that matter) can't parse static inline members correctly and will flag them as errors. Compile your project, the compiler itself shouldn't complain. – GlassBeaver Nov 04 '21 at 01:37

Why I can't define a static field in the declaration?

1 Answers1