Problem when including hpp & cpp files

Question

Hi everyone!
I'm having some trouble including header and source files in c++. Let's say I have these files (in the same folder):

// foo.hpp
#pragma once
#include <iostream>

void bar(void);

// foo.cpp
#include "foo.hpp"

void bar(void)
{
std::cout << "bar";
}

// test.cpp
#include "foo.hpp"

int main()
{
bar();
return 0;
}

When I compile with "g++ -Wall -Wextra test.cpp" it gives me the error "undefined reference to `bar()'" which seems to me that the compiler doesn't include the foo.cpp file... Where am I wrong?

Answer 1

You need to give both files as argument to g++

```
g++ -Wall -Wextra test.cpp foo.cpp
```

source:
http://www.math.uaa.alaska.edu/~afkjm/csce211/handouts/SeparateCompilation.pdf

Answer 2

Daniele , right.
Not sure if you noticed, but I have edited my answer to provide source from where I got answer. That text also mentions about makefiles. Using makefiles can be helpful if you have large project with many source files.

Answer 3

Thank you Martin Taylor !
Yeah, I've read a little about makefile (which I didn't know until this morning) and it's a very handy tool to use
Which build system would you suggest on Windows?

Answer 4

Thank you so much 🇮🇳Omkar🕉 , I didn't know you have to do that 😅
So for every source file I include, I have to tell the compiler where to find it, is that right?

Answer 5

That's really helpful, thank you 🇮🇳Omkar🕉 !

Answer 6

At the moment I'm using VS Code as my main editor, so I might try GNU make
On the other hand I was planning to download Visual Studio some day, so I may also download it directly!
Anyway, thank you so much for these infos Martin Taylor !