How to initialize private static members in C++?

Question

What is the best way to initialize a private, static data member in C++? I tried this in my header file, but it gives me weird linker errors: class foo { private: static int i; }; int foo::i = 0; I'm guessing this is because I can't initialize a private member from outside the class. So what's the best way to do this?

Answer 1

Hi there, to initialize a private static data member in C++, after you have declared the private static data member within the class, you use the class name and a binary scope resolution operator(::) with the variable name to assign a value without forgetting the data type. Note, this is done out of the class, not within the class, I guess that's where you are having an issue. Follow this example for a better understanding:-

#include <iostream>

using namespace std;

class Foo{

private:

static int i;

public:

Foo(){

i++; //increase the value of i when new object is created

}

static int getStaticVar() {

return i;

}

}; //Out of the Foo class

int Foo::i = 0; //initializing the private static variable i

main() {

Foo obj1, obj2, obj3; //three objects are created from Foo class

cout << "Number of objects: " << Foo::getStaticVar();

}