Thread: Problems with module

Hey everyone,
I'm sure at the end it's just a stupid mistake, but I need some help at a something i'm writing on atm.
The idea is to add, subtract etc. fractions. I want to put the functions in a header and call them in the programm itself.
My problem is, that it doesnt recognize the functions i wrote in the .c of the module.

I'm a total beginner so pls no hate

The .h

Code:

#ifndef rational_h#define rational_h
#endif


typedef struct {
    long numerator, denumerator;
}rational;


rational fraction1;
rational fraction2;
rational result;

The .c for the module

Code:

#include "rational.h"






rational addition(rational fraction1, rational fraction2,rational result)
{
    result.numerator = fraction1.numerator + fraction2.numerator;
    result.denumerator = fraction1.denumerator;
    return result;
};






rational subtraction(rational fraction1, rational fraction2, rational result)
{
    result.numerator = fraction1.numerator-fraction2.numerator;
    result.denumerator = fraction1.denumerator;
    return result;
};






rational multiplication(rational fraction1, rational fraction2, rational result)
{
    result.numerator = fraction1.numerator * fraction2.numerator;
    result.denumerator = fraction1.denumerator;
    return result;
};






rational division(rational fraction1, rational fraction2, rational result)
{
    long LMC;


    result.numerator = fraction1.numerator * fraction2.denumerator;
    result.denumerator = fraction1.denumerator*fraction2.numerator;


    if (fraction1.denumerator < fraction2.denumerator)
    {
        LMC=ggT(fraction1.denumerator, fraction2.denumerator);
    }
    else
    {
        LMC = ggT(fraction2.denumerator, fraction1.denumerator);
    }


    result.numerator *= (LMC / result.denumerator);
    result.denumerator = LMC;
    
    return result;
};






long ggT(long a, long b) 
{
    static long helper = 0;
    helper += b;






    if (helper%a == 0 && helper%b == 0)
    {
        return helper;
    }
    else 
    {
        return ggT(a, b);
    }
    
   


}

The program itself (in between the functions im gonna add something for the output)

Code:

#include "rational.h"

int main(void)
{
    addition(fraction1, fraction2);
    subtraction(fraction1, fraction2);
    division(fraction1, fraction2);
    multiplication(fraction1, fraction2);


    return 0;
}

Thanks everyone

You need to declare the functions in the header file, like so:

Code:

#ifndef RATIONAL_H
#define RATIONAL_H

typedef struct {
    long numerator, denumerator;
}rational;

rational addition(rational fraction1, rational fraction2,rational result);
rational subtraction(rational fraction1, rational fraction2, rational result);
rational multiplication(rational fraction1, rational fraction2, rational result);
rational division(rational fraction1, rational fraction2, rational result);
long ggT(long a, long b);

#endif

Also note the #endif goes at the end, since the whole header should be wrapped in the #define.

You should not declare variables in a header file, and should avoid global variables in general. Those variables can be declared locally where needed.

Your function calls don't provide enough arguments to the function:

Code:

// function call with two arguments
addition(fraction1, fraction2);

// function has three parameters
rational addition(rational fraction1, rational fraction2,rational result)
{
    result.numerator = fraction1.numerator + fraction2.numerator;
    result.denumerator = fraction1.denumerator;
    return result;
};

If you're returning "result", it does not have to be an argument.

First off, thanks to everyone

@john.c
rational.h:
-what do you mean by prototypes?
-english skills on point

rational.c:
-I did not convert the denominators, because of ggT. It's supposed to be a recursive approach on finding the lowest common divisor. I want to add this function in the part where the user inputs the fractions. So that I can change them there
This way I also only need to muliply the nominators
-and what do you mean with your last sentence?

Thank you a lot