static const in c++ class: undefined reference

Question

I have a class for local use only (i.e., its cope is only the c++ file it is defined in)

class A {
public:
    static const int MY_CONST = 5;
};

void fun( int b         


        

Answer 1

// initialize static constants outside the class

class A {
public:
    static const int MY_CONST;
};

const int A::MY_CONST = 5;

void fun( int b ) {
    int j = A::MY_CONST;  // no problem
    int k = std::min( A::MY_CONST, b ); // link error: 
                                            // undefined reference to `A::MY_CONST` 
}