How to access static members of a class

0 votes

I'm learning C++ and Qt, but even the simplest code that I copy and paste from a book produces problems.

On Ubuntu 10.04, I'm using g++4.4.2 with the QtCreator IDE. 

Is there a distinction between the syntax of the g++ compiler and those of other compilers? 

When I try to access static members, for example, something always goes wrong.

#include <iostream>
using namespace std;
class A
{
   public:
      static int x;
      static int getX() {return x;}
};
int main()
{
   int A::x = 100; // error: invalid use of qualified-name 'A::x'
   cout<<A::getX(); // error: : undefined reference to 'A::x'
   return 0;
}

I believe it is the same as stated here and here (isn't it?). 

So, what's the problem with the above code?

Jul 7 in C++ by Nicholas
• 5,020 points
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