Header files

nowber · 11-11-2009, 03:24 PM

Hi! I've just created a program (.c) and a header (.h) file with all the functions that I use in my program. Of course I don't have any main() function in the header file, which gives me an error: "Undefined symbol _main in module c0.ASM" if I run the .h file. I've also added a line, telling

Code:

#include "functions.h"

to the .c file and if I run the .c file, everything works without errors. So what is the correct way of creating a project? Should the .h file include a main function (which will result to multiple main() declaration) ?

p.s. I'm using Borland C++ 3.1

MK27 · 11-11-2009, 03:47 PM

Header files are actually not necessary at all, but if you want to use one, go ahead.

Anyway, no, there should not be a main() in the .h file. Each program can have only one main(). A header is not intended to used by itself.

nowber · 11-11-2009, 04:02 PM

Ok, so I have a functions.h header file (without the main function) and a main.c file. If I add both of them to a project and run it, I get multiple errors saying:

_function1 defined in module MAIN.C is duplicated in module FUNCTIONS.H
_function2 defined in module MAIN.C is duplicated in module FUNCTIONS.H
etc...

although I have defined them ONLY in functions.h file. The same error is produced for the array of records, that I've defined in functions.h. Any idea of what I'm doing wrong?

Here's a small example how it looks in general:

Code:

(functions.h)

int number (int low, int high);

struct rec {
	char name[33];
	};
struct rec arr[5]; // array of records


int number (int low, int high){
... some actions
}

(main.c)

#include "functions.h"

number(1,50)

MK27 · 11-11-2009, 04:09 PM

Quote:

Originally Posted by nowber

If I add both of them to a project and run it,

I am not familiar with the Borland compiler, so I presume this means you are doing something with the IDE?

Anyway, normatively you just include the .h file in your .c file:

Code:

#include "myheader.h"

Note that is not <myheader.h>. This presumes both files are in the same directory.

Then you just compile the .c file and the .h file will be included.

[edit] okay, it looks like that is what you are already doing....hmmm

11-11-2009, 03:24 PM	#1
nowber Registered User Join Date: Oct 2009 Posts: 16	Header files Hi! I've just created a program (.c) and a header (.h) file with all the functions that I use in my program. Of course I don't have any main() function in the header file, which gives me an error: "Undefined symbol _main in module c0.ASM" if I run the .h file. I've also added a line, telling Code: #include "functions.h" to the .c file and if I run the .c file, everything works without errors. So what is the correct way of creating a project? Should the .h file include a main function (which will result to multiple main() declaration) ? p.s. I'm using Borland C++ 3.1 Last edited by nowber; 11-11-2009 at 03:28 PM.
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11-11-2009, 03:47 PM	#2
MK27 subminimalist Join Date: Jul 2008 Location: NYC Posts: 3,944	Header files are actually not necessary at all, but if you want to use one, go ahead. Anyway, no, there should not be a main() in the .h file. Each program can have only one main(). A header is not intended to used by itself. __________________ Accuracy and integrity mean nothing if you don't make it past the censors...PYTHAGORAS
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11-11-2009, 04:02 PM	#3
nowber Registered User Join Date: Oct 2009 Posts: 16	Ok, so I have a functions.h header file (without the main function) and a main.c file. If I add both of them to a project and run it, I get multiple errors saying: _function1 defined in module MAIN.C is duplicated in module FUNCTIONS.H _function2 defined in module MAIN.C is duplicated in module FUNCTIONS.H etc... although I have defined them ONLY in functions.h file. The same error is produced for the array of records, that I've defined in functions.h. Any idea of what I'm doing wrong? Here's a small example how it looks in general: Code: (functions.h) int number (int low, int high); struct rec { char name[33]; }; struct rec arr[5]; // array of records int number (int low, int high){ ... some actions } (main.c) #include "functions.h" number(1,50) Last edited by nowber; 11-11-2009 at 04:08 PM.
nowber is offline

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