undefined reference for the extern variable in C++ header

Question

I have some code in C++:

// A.h
extern const char *names[3];

// B.cpp
#include "A.h"
const char *names[3] = {

   "Name1",
   "Name2"
   "Name3"
};

void getName()
{
    char *name;
    strncpy(name, names[0], 5);
};

// C.cpp
#include "A.h"

Then when I build it, it generate the following error:

undefined reference to `names' What is the reason and how to fix it?

Answer 1

You have some errors in the example, you provided, I assume you do not just copy/paste the source. Like the semicolon in line const char *names[3]; = {, or the missing comma in the list of strings next to "Name2"

So about your question. You should not include the A.h in you B.cpp, I mean the line #include "A.h" should be removed. You include the header file, and use the extern keyword only where you will use the *names pointer in other cpp files.