Multiple C++ Files

For beginners, there's a famous idiom in programming, called hello world! Maybe it's describing how a little baby who had just come out to the world. :-)

It's more common to see this hello world source code:

$ vim hello.cpp
#include

int
main(){
std::cout<<"hello world!\n";
return 0;
}


Compile it with g++ and execute it:

$ g++ -o hello hello.cpp
$ ./hello


It's the basic. How about if we manage to build a complex program? We divide it. We made several files. Here's the hello world with multiple files version. In this example there are three files:

• helloworld.cpp


• helloworld.h


• main.cpp

First, the helloworld.cpp

#include "helloworld.h"
#include
using namespace std;

void hello_world(){
cout << "hello world!\n";
}


Then the helloworld.h

#ifndef _HELLOWORLD_H
#define _HELLOWORLD_H

#include

void hello_world();

#endif


Last, the main.cpp

#include "helloworld.h"
#include
using namespace std;

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


Then it's time to compile it. How to do it?

g++ -o hello main.cpp helloworld.cpp


Execute it!

$ ./hello
hello world!


Reference, accessed on 2010.10.01 14:20 (GMT+7).