Help with multiple cpp files

I'm having problems getting any programs with multiple cpp files to compile. I am using Dev-C++.
Here are my files:

Code:

---

//main.cpp
#include <iostream>
#include "functions.h"

using namespace std;

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

---

Code:

---

//functions.h
void newFunction();

---

Code:

---

//functions.cpp
#include <iostream>
#include "functions.h"

void newFunction()
{
cout << "Hello \n";
}

---

Here is the error:

Code:

---

C:\Dev-Cpp\functions.cpp `cout' undeclared (first use this function)

---

I have tried to get several of these multi-cpp programs to compile but they all give various errors. Even a very simple one like this. I think I must be missing something that should be obvious here.

Thanks!

This has less to do with having multiple source files and more to do with incorrect code in a source file. In particular, you are using std::cout without fully qualifying the name. As such, a using declaration or using directive should be present, but none are present. The using directive that you do have is present in another source file.

You will need to prefix cout with std::, or add using namespace std, or some similar.

--
Mats

Thank you both for the quick reply. Still getting errors though strangely. I've updated functions.cpp so now it looks like this

Code:

---

#include <iostream>
#include "functions.h"

using namespace std;

void newFunction()
{
cout << "Hello \n";
}

---

[Linker error] undefined reference to `std::string::size() const'
[Linker error] undefined reference to `std::string::operator[](unsigned int) const'
[Linker error] undefined reference to `std::ios_base::Init::Init()'
C:\Dev-Cpp\Makefile.win [Build Error] [GAYPROJECT.exe] Error 1


Any ideas?

Sounds like Dev-C++ is invoking gcc instead of g++, so the standard library is not linked to by default. Unfortunately, I do not have a copy of Dev-C++ around to check what are the required changes to make in the settings.

Quote:

---

Originally Posted by laserlight

Sounds like Dev-C++ is invoking gcc instead of g++, so the standard library is not linked to by default. Unfortunately, I do not have a copy of Dev-C++ around to check what are the required changes to make in the settings.

---

ok thanks, i thought it would be something that had to do with the linker.

Quote:

---

Originally Posted by Sclorch

ok thanks, i thought it would be something that had to do with the linker.

---

In a way, it does, because this is a linking problem. Did you create a C project instead of a C++ project?

Quote:

---

Originally Posted by laserlight

In a way, it does, because this is a linking problem. Did you create a C project instead of a C++ project?

---

Yep, am I wrong in assuming that the compiler will just link all of my files in a project together for me? Or do I have to manually link them all together?

Here were the steps I took:

Created new project (win32 console)
Added blank files into project.
Renamed those blank files to the source and header files.
Added the code
Then just clicked "compile and run"

Am I missing a step here? Thanks again

Quote:

---

Originally Posted by Sclorch

Yep, am I wrong in assuming that the compiler will just link all of my files in a project together for me? Or do I have to manually link them all together?

---

It should, but the problem here is that it is not linking to the C++ standard library.

Quote:

---

Originally Posted by Sclorch

Am I missing a step here?

---

They look fine to me. I suggest that you start a new project and test with:

Code:

---

#include <iostream>
#include <string>

int main()
{
    using namespace std;

    string text = "hello world!";
    cout << text << endl;
}

---

If you do not get any linker errors, you might to try adding more files to that working project.

Quote:

---

Originally Posted by laserlight

It should, but the problem here is that it is not linking to the C++ standard library.


They look fine to me. I suggest that you start a new project and test with:

Code:

---

#include <iostream>
#include <string>

int main()
{
    using namespace std;

    string text = "hello world!";
    cout << text << endl;
}

---

If you do not get any linker errors, you might to try adding more files to that working project.

---

Cool I wrote a small program that uses 2 cpp and 1 new h file that I wrote. Working great so far! thanks