How to link an object file into an existing project in C++

[skiman1979]

Hi all,

I've been using Linux as a desktop OS for a while now, but only recently started getting into development with it. Sadly, I'm used to Visual Studio holding my hand and doing all the compiling, linking, and building for me.

I have a C++ class consisting of a .h and .cpp file that I want to compile into an object and give that object to a customer without giving them the source code. Then they can include this object in their software and use it.

So far, I was able to compile the class with the following...

g++ -c classname.h classname.cpp

This gives me classname.h.gch and classname.o

My question is, how do I go about including these objects in an existing code base to compile the end application? I just want to give the customer the .gch and .o files, and not the .h and .cpp files.

For example, I have a small .cpp file, which just has a main() and a few calls into the class functions from classname. If I try to do something like...

g++ classname.o tester.cpp -o tester

it complains that classname.h is not found, but I don't want to provide them with source code. Note: tester.cpp would be the customer's code, classname is just the class we're providing them.

[gerard4143]

Never used pre-compiled header but I found this link:

Precompiled Headers - Using the GNU Compiler Collection (GCC)

...Gerard4143

[gerard4143]

Makefile

test: getsetx.o test.o getsetx.h.gch
	gcc getsetx.o test.c -o test

test.o: test.c
	gcc -c test.c

getsetx.o: getsetx.c
	gcc -c getsetx.c

getsetx.h.gch: getsetx.h
	gcc -c getsetx.h

getsetx.c

int x = 0;

int getx()
{
	return x;
}

void setx(int val)
{
	x = val;
}

getsetx.h

int getx();

void setx(int val);

test.c

#include "getsetx.h"
//to get this to work I had to include getsetx.h  first
#include <stdio.h>
#include <stdlib.h>


int main(int argc, char**argv)
{
	setx(123);
	fprintf(stdout, "ans->%d\n", getx());
	exit(EXIT_SUCCESS);
}

Now if you call make -f makefile and then delete getsetx.h the executable test will run without incident...The same should hold true for g++...Gerard4143

[skiman1979]

Thanks Gerard. I actually did something similar to this after my initial post. Using your above example, I would only give the customer getsetx.h.ghc and getsetx.o. They would provide test.c and execute

gcc getsetx.o test.c -o test

without any access to getsetx.h or getsetx.c.