I'm stumped, put me in the right direction?

[Zexanima]

I'm working on an exercise from a book(C++ without fear) as follows:

Write a program that uses the Fraction class by setting a series of
values by calling the “set” function: 2/2, 4/8, -9/-9, 10/50, 100/25. Have the program print out the results and verify that each fraction was correctly simplified.

This is the best way I could think to do it, but I'm getting errors I don't know how to handle like "error: name look up of 'i' changed for new ISO 'for' scoping"
Any help would be nice, and maybe something to explain why I got these errors.

#include <iostream>
#include <string>
using namespace std;

class Fraction {
    
    private:
        int num, den; // Numerator and denominator.
    public:
        void set(int n, int d)
        {num = n; den = d; normalize();}
        int get_num() {return num;}
        int get_den() {return den;}
    private:
        void normalize(); // Convert to standard form.
        int gcf(int a, int b); // Greatest Common Factor.
        int lcm(int a, int b); // Lowest Common Denom.
};
int main() {
    int a, b;
    string str;
    Fraction fract;
    Fraction fc[5];
    
        while (true) {
            
            for (int i=0;i<=4;i++){
            
            cout << "Enter numerator: ";
            cin >> a;
            cout << "Enter denominator: ";
            cin >> b;
            fc[i] = fract.set(a,b);
            }
}
cout << "Your fractions are: \n";
    for(int i=0;i<=AV;i++){
        cout << fc(i) << endl;
    }
            
        

cout << "Do again? (Y or N) ";
cin >> str;

        if (!(str[0] == 'Y' || str[0] == 'y'))
            break;
}
system("PAUSE");
return 0;
}
// ---------------------------------------------------
// FRACTION CLASS FUNCTIONS
// Normalize: put fraction into standard form, unique
// for each mathematically different value.
//
void Fraction::normalize(){
// Handle cases involving 0
    if (den == 0 || num == 0) {
        num = 0;
        den = 1;
}
// Put neg. sign in numerator only.
    if (den < 0) {
        num *= -1;
        den *= -1;
}
// Factor out GCF from numerator and denominator.
    int n = gcf(num, den);
        num = num / n;
        den = den / n;
}
// Greatest Common Factor
//
int Fraction::gcf(int a, int b) {
    if (b == 0)
        return abs(a);
    else
        return gcf(b, a%b);
}
// Lowest Common Multiple
//
int Fraction::lcm(int a, int b){
    int n = gcf(a, b);
        return a / n * b;
}

[Gaminic]

Well, for one thing, line 38 calls "fc(i)", but there is no such function. Do you mean fc[i]? Even then, fc[i] is a Fraction object, which has no << operator, since you didn't define one. Even if you had, it still wouldn't output anything (or just nonsense), because fc[i] is never assigned a value: set() has no return value!

Also, just a minor point: you're using a while() loop, yet instead of controlling it, you're letting it run wild until it hits "break". Why not simply use a boolean to control the condition? Does the same, but much prettier.

[Zexanima]

I see how I could fix it now, thanks.