using multiple source files

[Duncan]

I'm experimenting using multiple source files. Here's a short example of what I think SHOULD work...:

///functions.h///

#ifndef FUNCTIONS_H
#define FUNCTIONS_H

void print(char*);
int increment(int);
int sum(int,int);

#endif 

///functions.cpp///

#ifndef FUNCTIONS_CPP
#define FUNCTIONS_CPP

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

void print(char* input)
{
  cout<<input<<endl;
}

int increment(int a)
{
  return (a+1);
}

int sum(int a, int b)
{
  return (a+b);
}

#endif 

///main.cpp///

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

int main()
{
  print("hello world!");
  int foo=5;
  int foo2=increment(foo);
  cout<<"foo: "<<foo<<endl;
  cout<<"foo2: "<<foo2<<endl;

  cout<<"sum(foo,foo2): "<<sum(foo,foo2)<<endl;

  return 0;
}

This makes sense to me... But when i try compiling main.cpp I get a bunch of "Undefined symbols"

This leads me to think that the functions are not defined...

The program works as expected if I #include "functions.cpp" in main.cpp... but I thought one only had to include the .h file and the linker would link all the symbols for you...

Please correct me how I am wrong.

[firedraco]

Try removing the protection from the .cpp file, you only need it for header files.

[helios]

Sounds like you didn't add functions.cpp to the project.

[Duncan]

oh good point about the protection on the cpp file... lol that was foolish.

Unfortunately, that didn't fix the issue...

and helios, I'm not really in a project environment... I'm using the command line like "g++ -o myProgram main.cpp"

[helios]

Try g++ -o myProgram main.cpp functions.cpp

[Duncan]

oh, nice call helios that worked.

Though it would be a little tedious to include every single .cpp file with the g++ command... is it safe to do "g++ -o myProgram *.cpp" ??

[helios]

I'm not sure. I think it's worth a try.

And about the tediousness, that's exactly why the GNU build system was created.

[Duncan]

well it did work when i tried it... so that's pretty neat.

kthx :D

[Mythios]

Wheres the using namespace std;

[Duncan]

oh.. good call Mythios.. I guess i forgot that.

Oh well, it was only supposed to be a rough example...