C++ undefined reference

[danikaze]

Hello.

I have a code like this:

class A {
    ...
  protected:
    static int var;
    ...
}
int A::var;


class B : public A {
  ...
  void method() {
    ...
    var = whatever;
    ...
  }
}

It compiles, but the linker says...
undefined reference to A::var

where's the problem?

thanks in advance

[helios]

What exactly are you trying to do on line 7?

[danikaze]

when you declare a static var in a class, it needs to be declared outside the class, so it has memory assignment.

most of people forgot it, but that's not the problem

[jsmith]

Yes, but put the actual instantiation of var inside a .cpp file, not in the header file. Variables in header files are EVIL.

[helios]

Line 6 has a missing semicolon, then.
And so does line 17.