Error: there is no corresponding function to call 'fraction :: add (fraction &, fraction &)'

[Error] no matching function for call to 'fraction::add(fraction&, fraction&)'
line 105 which is
f3.add( f1, f2);

      

        
        
        
      

    

This is the error message I get when I try to compile.

Instance: I'm trying to create a "faction" class that allows my instructor to preset int main () to execute. I've been building the bare-bones class so far and am trying to compile it to see if it works.

  'My class:
class fraction
{
private:
long num, den; 
public:
void setNum(long i_num)
{
    num=i_num;
}
void setDen(long)
{
}
long getNum()
{
return num; 
}
long getDen()
{
return den;
}

fraction()
{
    num = 1;
    den = 1;
}
fraction(int n, int d)
{
    num = n;
    if (d==0) 
    {
        cout << "Cannot divide by zero" << endl;
        exit(0); // will terminate the program if division by 0 is attempted
    }
    else
        den = d;
}

fraction add(fraction otherFraction)
{
    int n = num*otherFraction.den+otherFraction.num*den;
    int d = den*otherFraction.den;
    return fraction(n/gcd(n,d),d/gcd(n,d));
}

fraction sub(fraction otherFraction)
{
    int n = num*otherFraction.den-otherFraction.num*den;
    int d = den*otherFraction.den;
    return fraction(n/gcd(n,d),d/gcd(n,d));
}

fraction mult(fraction otherFraction)
{
    int n = num*otherFraction.num;
    int d = den*otherFraction.den;
    return fraction(n/gcd(n,d),d/gcd(n,d));
}

fraction div(fraction otherFraction)
{
    int n = num*otherFraction.den;
    int d = den*otherFraction.num;
    return fraction(n/gcd(n,d),d/gcd(n,d));
}


int gcd(int n, int d)
{
    int remainder;
    while (d != 0)
    {
        remainder = n % d;
        n = d;
        d = remainder;
    }
    return n;
}
void print() // Display method
{
    if (den == 1) // e.g. fraction 2/1 will display simply as 2
        cout << num << endl;
    else
        cout << num << "/" << den << endl;
}
};'

      

        
        
        
      

    

My instructor int main ():

int main ( )
{ // define seven instances of the class fraction
fraction f1, f2, f3, f4, f5, f6, f7;
//set values for the numerator and denominator to f1 and print 
//them
f1.setDen( 2L);
f1.setNum( 0L);
f1.print();

//set values for the numerator and denominator to f2 and print them
f2.setDen( 4L);
f2.setNum( 3L); 
f2.print();
f3.add( f1, f2);
f3.print();
f4.sub( f1, f2);
f4.print();
f5.mult( f1, f2);
f5.print();
f6.div( f1, f2);
f6.print();
f7.inc(f1);
f7.print(f1);

      

        
        
        
      

    

My instructor told us not to edit main () in any way.

I traced it back to a method in the class

    fraction add(fraction otherFraction)
{
    int n = num*otherFraction.den+otherFraction.num*den;
    int d = den*otherFraction.den;
    return fraction(n/gcd(n,d),d/gcd(n,d));
}

      

        
        
        
      

    

How do I go about passing variables to main () so that they work in the class? I was only taught one way to do things, and this is my first OO class. He teaches different ways of organizing and I don't understand. He hasn't emailed me yet in about a week (online class).

Any hints / advice would be much appreciated. Thank.