Undefined reference to defined static private variable

Question

i've got a problem dealing with static private variables. Here is my code.

ClassA.h:

class ClassA{
    static int a;
public:
    int getA();
};

Class.cpp:

#include "ClassA.h"

int ClassA::a = 9001;

int ClassA::getA(){
    return a; //<--- Undefined reference to ClassA::a
}

As you can see, i defined the static variable in the implementation file, as it has been said over and over, i also did this to other static member of other classes, and they work without any problem, but this one doesn't. Does anyone have any solutions?

I see nothing wrong with it. Check the semicolon as Madsen suggested, nothing more. — Marco A., Apr 11 '14 at 10:53
This code is fine. There must be some other detail in your actual code that you've overlooked. — M.M, Apr 11 '14 at 12:35

S.C. Madsen · Answer 1 · 2014-04-11T11:34:35.137

0

Maybe ClassA is missing a ; at the end of its declaration?

I can't spot any errors in the code you've provided. Perhaps ClassA is defined inside a namespace?

edited Apr 11 '14 at 11:34

answered Apr 11 '14 at 10:51

S.C. Madsen

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score -2 · Answer 2 · answered Apr 11 '14 at 10:53

-2

declare

int ClassA::a; in .h itself

as below:

class ClassA{
    static int a;
public:
    int getA();
};
int ClassA::a = 9001;

Also, Your class A declaration does not end with a semicolon.

answered Apr 11 '14 at 10:53

Dr. Debasish Jana

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added the semicolon at the end of Class A declaration? – Dr. Debasish Jana Apr 11 '14 at 10:57
Yes, it was an error in my trascription of the code, it was already there in the .h file in my computer. – TimeZero Apr 11 '14 at 10:59
Not to me, maybe because i'm using Eclipse C++, but the error remains. – TimeZero Apr 11 '14 at 11:05
1

Defining it in the header is a bad idea, because if two units include that header then the behaviour is undefined. – M.M Apr 11 '14 at 12:34

Undefined reference to defined static private variable

2 Answers2