Hi,

I'm a university student taking a module in C programming. While I am enjoying the module, we have recently been set an assignment that has pushed me. I have to use .h files within my code to tie together 4 different questions.

Code:
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include "element_sort.h"
#include "wavelength.h"
#include "quadratic.h"
#include "element_info.h"



int decision;

int main()

{
	printf("This program has the ability to do four tasks. "
			"\n\nPlease pick the corresponding number related"
			" to the task you wish to be done.\n\n"
			"1. Sort elements stored on file by either name or abundance.\n"
			"2. Find maxima from data on wavelengths and absorbances.\n"
			"3. Root Finding\n"
			"4. Element Database");
	while(1)

	{
			scanf("%i", &decision);

		if (decision == 1)
		{
			printf("You have selected option 1");
			element_sort();
		}
		if (decision == 2)
		{
			printf("You have selected option 2");
			wavelength();
		}
		if (decision == 3)
		{
			printf("You have selected option 3");
			quadratic();
		}
		if (decision == 4)
		{
			printf("You have selected option 4");
			element_info();
		}
		else
		{
			printf("Invalid Number");
			continue;
		}
		return 0;
	}
}
This is what I have so far. Not much I know, but I've only just started. Each of the .h files that this code 'links' to has something akin to
Code:
int wavelength();
and that alone.

My problem arises when I try to build I get two errors, with Assessment 2 being the title of the piece.

make: *** [Assessment2] Error 1 Assessment 2
symbol(s) not found Assessment 2

unfortunately these both do not reference anywhere in particular that the error is to be found.
Please note I have used Eclipse before and it has worked. I also get a similar problem when I attempt to use xcode.
Any help would be very much appreciated.

Thanks