C - how to include own headers kept in separate folder

Question

First of all I am pretty much a beginner, so I am not sure how to explain what I need but I'll give it a try. (I searched but couldn't find a complete answer).

I am learning C on my own and using Code Blocks.

I want to create my own mini-library of custom functions to use in my programs.

I have a folder called "C". Inside "C", I have a folder called "Exercises" where I do all the little projects from a book.

Also inside "C", I wanna have another folder called "MyC" in which I would keep my own header files and the .c files containing the implementations of my custom functions. For example, these .h and .c would be saved in "MyC":

//test.h

#ifndef _TEST_H
#define _TEST_H

int mySum(int, int);

#endif // _TEST_H

//test.c

#include <stdio.h>
#include "test.h"

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

So now, what I'm trying to do is to be able to create a new project in "Exercises" and not having to bring a copy of both test.h and test.c into the project, but instead just #include my test.h and do something like:

//testMain.c

#include <stdio.h>
#include <test.h>

int main(void)
{
    printf("\n2 + 1 = %d", mySum(2, 1));

    return 0;
}

I know that <> are for the standard headers, but quotes are for headers in the current folder, and that's what I don't want.

Is it possible to do this? How?

I've read about going into settings>compiler and on Search Directories add the path where I have the header but didn't work. It gives me an error "undefined reference to 'mySum'" I tried quotes and brackets on the #include.

Can you guys please give a step-by-step for what it needs to be done to be able to do this?

Answer 1

for headers

If you want to move back one folder, do that: #include "../something.h".

In your case, just do this: #include "../MyC/test.h"

.. simply means go back one directory.

If you dislike doing it like that, or you want to simply #include "test.h", you can do it using -I compiler parameter, like this:

-I'../MyC/'

for c files

You need to do a simmiliar thing in compiler parameter.

gcc testMain.c ../MyC/test.c

Just remember that, .. means go back one directory!