linking static class member function throws undefined reference error c++

Question

I've gone through many similar threads on this kind of question but I'm still unable to resolve this error. Any help would be appreciated.

/*samp.h header file*/

#include<iostream>
using namespace std;

class test
{
private:
test();
public:
static void const_caller();
};

/*samp.cpp file*/

#include<iostream>
using namespace std;

class test
{
private:
test()
{
cout<<"priv cont called\n";
}
public:
static void const_caller()
{
cout<<"calling priv const\n";
}
};

/*main.cpp file */

#include"samp.h"
using namespace std;

int main(int argc, char **argv)
{
test::const_caller();
}

when I do

g++ samp.cpp main.cpp -o main.out

I get this error

/usr/bin/ld: /tmp/ccHZVIBK.o: in function `main':
main.cpp:(.text+0x14): undefined reference to `test::const_caller()'

which I'm unable to resolve since quite some time now.

The shown code should not even compile, much less get to the link stage. What exactly is the shown code including? Most of the `#include`s are missing what's actually getting included. Furthermore, even what's left of the shown code there are obvious fundamental issues. You do not define class methods by copy/pasting the entire class declaration, and then defining class methods inline. C++ does not work this way. Perhaps [you can try a better C++ book](https://stackoverflow.com/questions/388242/the-definitive-c-book-guide-and-list)? — Sam Varshavchik, May 22 '20 at 21:03

score 1 · Answer 1 · answered May 22 '20 at 21:04

With your posted code, the .cpp file contains its own definition of the class that has the same name as the class in the .h file but it is really a different class.

In the .cpp file, you need to use:

test::test()
{
   cout<<"priv cont called\n";
}

void test::const_caller()
{
   cout<<"calling priv const\n";
}

score 1 · Accepted Answer · answered May 22 '20 at 21:10

In the samp.cpp file you define test class again.

You need to include samp.h header and implement methods of test class:

#include "samp.h"

using namespace std;

test::test()
{
    cout << "priv cont called\n";
}

void test::const_caller()
{
    cout << "calling priv const\n";
}

linking static class member function throws undefined reference error c++

2 Answers2