分数计算器c++

我正试图找出一种方法，将两个分数相加，并根据输出获得最低形式或混合形式的结果分数，但问题是，当我输入两个分母相同的分数时，它只会把其他一切都搞砸这是我到目前为止的代码

#include<cmath>
#include<iostream>
using namespace std;
void reduce_fraction(int &numerator, int &denominator);
void addFractions(int numerator1Par, int denominator1Par, int numerator2Par, int              denominator2Par);
int main(){
    int numerator1 = 0;
    int denominator1 = 0;
    int numerator2 = 0;
    int denominator2 = 0;
    int unfactoredNumerator = 0;
    int resultDenominator = 0;
    int mixedNumberRemainder = 0;
    int mixedNumberWhole = 0;
    int reducedNumerator = 0;
    int reducedDenominator = 0;
    int result;
    int greatCommonDenominator;
    cout << "Enter first numerator:   ";
    cin >> numerator1;
    cout << "Enter first denominator: ";
    cin >> denominator1;
    cout << endl;

    cout << "Enter second numerator:   ";
    cin >> numerator2;
    cout << "Enter second denominator: ";
    cin >> denominator2;
    cout << endl;
    if (denominator1 == denominator2)
    {
            result = numerator1 + numerator2;
            if (unfactoredNumerator>resultDenominator){
                    int a = unfactoredNumerator / resultDenominator;
                    int b = unfactoredNumerator - (a*resultDenominator);
                    cout << numerator1 << "/" << denominator1 << " + " << numerator2 << "/" << denominator2 << " = " << a << " " << b << "/" << resultDenominator << endl;
            }
            else
            {
                    if (unfactoredNumerator == 0 && resultDenominator == 0)
                            greatCommonDenominator = 1;
                    else if (resultDenominator == 0)
                            greatCommonDenominator = unfactoredNumerator;
                    else if (unfactoredNumerator != 0) {
                            int a = unfactoredNumerator, b = resultDenominator;
                            while (a != b)
                                    if (a < b)
                                            b -= a;
                                    else
                                            a -= b;
                            greatCommonDenominator = b;
                    }
                    cout << numerator1 << "/" << denominator1 << " + " << numerator2 << "/" << denominator2 << " = " << (unfactoredNumerator / greatCommonDenominator) << "/" << (resultDenominator / greatCommonDenominator) << endl;
            }
    }
    else
    {
            addFractions(numerator1, denominator1, numerator2, denominator2);
    }
    system("pause>nul");
    return 0;
}
void reduce_fraction(int &numerator, int &denominator)
{
    for (int i = denominator * numerator; i > 1; i--) {
            if ((denominator % i == 0) && (numerator % i == 0))
            {
                    denominator /= i;
                    numerator /= i;
            }
    }
}
void addFractions(int numerator1Par, int denominator1Par, int numerator2Par, int denominator2Par)  {
    int unfactoredNumerator;
    int resultDenominator;
    int greatCommonDenominator;
    unfactoredNumerator = numerator1Par * denominator2Par + numerator2Par * denominator1Par;
    resultDenominator = denominator1Par * denominator2Par;
    if (unfactoredNumerator>resultDenominator){
            int a = unfactoredNumerator / resultDenominator;
            int b = unfactoredNumerator - (a*resultDenominator);
            cout << numerator1Par << "/" << denominator1Par << " + " << numerator2Par << "/" << denominator2Par << " = " << a << " " << b << "/" << resultDenominator << endl;
    }
    else
    {
            if (unfactoredNumerator == 0 && resultDenominator == 0)
                    greatCommonDenominator = 1;
            else if (resultDenominator == 0)
                    greatCommonDenominator = unfactoredNumerator;
            else if (unfactoredNumerator != 0) {
                    int a = unfactoredNumerator, b = resultDenominator;
                    while (a != b)
                            if (a < b)
                                    b -= a;
                            else
                                    a -= b;
                    greatCommonDenominator = b;
            }
            cout << numerator1Par << "/" << denominator1Par << " + " << numerator2Par << "/" << denominator2Par << " = " << (unfactoredNumerator / greatCommonDenominator) << "/" << (resultDenominator / greatCommonDenominator) << endl;
    }
}