Classes help

[Belcross]

I wasn't sure what to name the thread, but I have a few questiong. I've written a program to add, subtract, multiply, and divide for class. It all works well except I need to add a few odds and ends. I've added the reduction part of the code but it's not working. I also need to add in a way top automatically input a 1 if the user hits enter w/o entering a number.

The only thing left is I need to ensure the denom is not a 0 or negative. I was thinking something like

if(denom >= 0)
cout<<"please enter a valid denominator\n";
cin>>denom;
a.set_den(denom);

which works but I need to make it recursive or add in a check. I'm trying to keep my code from becoming bloated as well, so can I write that as a single code also w/o needing to have the code twice, once for each input of the denom. I'm listing my code below, thanks in advance.

//Define class Fraction Num\Denom int only, no float***
//Program operations +,-,*,/ to (overload)***
//When a user inputs a blank input build a constructor that enters "1"
//Research Euclidean Algorithm to find GCD for reduction.
//Class checks, no 0 or "-" in denominator.
//Minimal code in "main***

#include <iostream>
#include <cassert>
#include <cmath>
using namespace std;


class Fraction

{
int num;
int den;


public:

//public function can access private function's and set variables

void set_num(int numpub)
{num=numpub;};

void set_den(int denpub)
{den=denpub;};

int get_num()
{return num;};

int get_den()
{return den;};


int gcd(int set_num, int set_den)
{
if(set_den == 0) return set_num;
else
{return gcd(set_den, set_num % set_den);};
}


Fraction(int a, int b)
{set_num(a); set_den(b);};
Fraction(){};

//Fraction x is the b input and the default w/ no x. is the a input
Fraction operator +(Fraction x)
{
Fraction result;
result.set_num(num*x.get_den()+den*x.get_num());
result.set_den(den*x.get_den());
return result;
}

Fraction operator -(Fraction x)
{
Fraction result;
result.set_num(num*x.get_den()-den*x.get_num());
result.set_den(den*x.get_den());
return result;
}
Fraction operator *(Fraction x)
{
Fraction result;
result.set_num(num*x.get_num());
result.set_den(den*x.get_den());
return result;
}
Fraction operator /(Fraction x)
{
Fraction result;
result.set_num(num*x.get_den());
result.set_den(den*x.get_num());
return result;
}



};



int main()

{
Fraction a;
Fraction b;
Fraction c;
Fraction out;
int numer;
int denom;
char oper;


cout<<"Please enter your FIRST Numerator and Denominator:\n";
cin>>numer >> denom;
a.set_num(numer); a.set_den(denom);


if(denom >= 0)
cout<<"please enter a valid denominator\n";
cin>>denom;
a.set_den(denom);


cout<<"Please enter the SECOND Numerator Denominator:\n";
cin>>numer >> denom;
b.set_num(numer); b.set_den(denom);

if(denom >= 0)
cout<<"please enter a valid denominator\n";
cin>>denom;
b.set_den(denom);

//operation, c is the new output after the operation is complete.
cout<<"Choose operation of '+,-,*,/'\n";
cin>>oper;
switch(oper)
{
case '+':c=a+b;
break;
case '-':c=a-b;
break;
case '*':c=a*b;
break;
case '/':c=a/b;
break;
default: cout<<"Invalid Operator!\n";
break;
}




cout<<"Success!\n"<<c.get_num()<<"/"<<c.get_den()<<endl;

return 0;

};

/*
int gcd(int set_num, int set_den)
{
if(set_den == 0) return set_num;
else
{return gcd(set_den, set_num % set_den);};
}
*/