CODEWITHSUNDEEP
c++headernamespaces
Dingus
Dingus

Reputation: 65

C++ How do you solve namespaces in headers becoming undefined?

So I am currently making a small prototype for a bigger project I'm working on and I've gotten completely stuck on it. I am rather new to c++ and haven't worked with headers or namespaces before ever. The issue is that when i try to use my created namespace it fails completely and the compiler (clang) returns undefined.

#include <iostream>
#include "bark.hpp"

using namespace bark;

int main() {
    bark::woof();
}

Header file:

#pragma once
#ifndef FUNCTIONS_HPP
#define FUNCTIONS_HPP

namespace bark {
    void woof();
}

#endif

file with functions:

#include <iostream>
#include "bark.hpp"

void woof() {
    std::cout << std::endl << "woof" << std::endl;
}

Upvotes: 2

Views: 130

Answers (1)

cigien
cigien

Reputation: 60208

In the implementation file, this definition:

void woof() 
{
 // ...
}

defines a function woof in the global namespace. So when you make the call:

bark::woof();

in the main function, there is no bark::woof defined, and the linker will refuse to link the program.

To correctly define the woof from namespace bark, you need to either qualify it:

void bark::woof() 
{
 // ...
}

or else introduce the namespace bark, and define it inside:

namespace bark
{
  void woof() 
  {
    // ...
  } 
}

Upvotes: 6

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