C++ static variable member of class

Question

Hi guys. I am a little bit confused with this:

#include "stdafx.h"
#include <iostream>

using namespace std;

class A
{
public:
static int a;
};

int main()
{
int A::a = 8;
cout << A::a << endl;
return 0;
}

the example above is not working but this code:

#include "stdafx.h"
#include <iostream>

using namespace std;

class A
{
public:
static int a;
};

int A::a = 8;
int main()
{
cout << A::a << endl;
return 0;
}

this is working fine. My question is why the first one is not working but the second one is okay ?

Answer 1

Because static variables need to have global scope when initialized. The compiler can't see it when it's initialized inside main().