How can you define a static data member of type const std::string?
c++, class, constants, static-members, string
Solution
Since C++17, you can use an inline variable:
// In a header file (if it is in a header file in your case)
class A {
private:
inline static const string RECTANGLE = "rectangle";
};
Prior to C++17, you have to define your static member outside the class definition and provide the initializer there.
// In a header file (if it is in a header file in your case)
class A {
private:
static const string RECTANGLE;
};
// In one of the implementation files
const string A::RECTANGLE = "rectangle";
The syntax you were originally trying to use (initializer inside class definition) is only allowed with integral and enum types.
Problem
I'd like to have a private static constant for a class (in this case a shape-factory). I'd like to have something of the sort. ``` class A { private: static const string RECTANGLE = "rectangle"; } ``` Unfortunately I get all sorts of error from the C++ (g++) compiler, such as: ISO C++ forbids initialization of member ‘RECTANGLE’ invalid in-class initialization of static data member of non-integral type ‘std::string’ error: making ‘RECTANGLE’ static This tells me that this sort of member design is not compliant with the standard. How do you have a private literal constant (or perhaps public) without having to use a #define directive (I want to avoid the uglyness of data globality!)