spreading source across folders

[rowdy]

i am having trouble with getting source files to compile when they include headers in different folders.

eg.

src/folderA/constants.h:

#define constant1 51

src/folderB/program.c

#include "constants.h"
#include <iostream>
int main () {
	cout << constant1;
	return 0;
}

src/makefile:

program: program.o
	$(CC) program.o -o program
program.o: src/folderB/program.c
	$(CC) -c src/folderB/program.c -o program.o

This won't compile since program.c doesn't know where constants.h is,

[D_Drmmr]

src/folderA/constants.h:

#define constant1 51

src/folderB/program.c

#include "constants.h"
//...

This won't work, because you're telling the compiler to look for the constants.h file in the same location as the program.c file. Either use a relative path to the header file or use #include <> and set 'folderA' as an include directory.

[Richard.J]

Nope.
#include <>
should be used for system files (such as time.h etc)

What needs to be done is simply

INC_DIRS = src/folderA

program: program.o
	$(CC) program.o -o program

program.o: src/folderB/program.c
	$(CC) -c src/folderB/program.c -I$(INC_DIRS) -o program.o

using "" or <> for include files works more or less equivalent, except that the order in that direcories are searched for the files differs. I have read the recommendation to use "" for own files and <> for system files.

[Muthuveerappan]

Richard.J is spot on.

Use the -I for every new directory to be included.

Below is applicable only for templates:
Just be a little careful while using templates, you would need implementation of a function to compile the application file.