define static function outside the class and access static value .h and .cc files

Question

 //foo.h
 class Foo 
  {
    private:
      static int number;

    public: 
      static int bar();
  };

//foo.cc
#include "foo.h"

 int Foo::bar() 
 {
   return Foo::number;
 }

this is not working. I want to define a static function outside the class definition and access a static value.

undefined reference to `Foo::number'

The static value was never defined. Add `int Foo::number;` in foo.cc — Mooing Duck, Oct 26 '11 at 20:37

score 8 · Accepted Answer · edited May 23 '17 at 12:14

8

You just declared the static member you need to define it too. Add this in your cpp file.

int Foo::number = 0;

This should be a good read:

what is the difference between a definition and a declaration?

edited May 23 '17 at 12:14

Community

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answered Oct 26 '11 at 20:37

Alok Save

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thanks! I didn t know that this is possible when settig Foo::number as private – thomas050903 Oct 26 '11 at 20:57

score 2 · Answer 2 · answered Oct 26 '11 at 20:37

2

you have to define Foo::number:

// foo.cc
...
int Foo::number(0);

answered Oct 26 '11 at 20:37

justin

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score 1 · Answer 3 · answered Oct 26 '11 at 20:37

1

You have declared Foo::number you have to add a definition. In your cpp file Add this line

int Foo::number = 0;

answered Oct 26 '11 at 20:37

rerun

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define static function outside the class and access static value .h and .cc files

3 Answers3