View difference between Paste ID: QMKRjEyQ and JStbWBRT

 #include <iostream>
 #include <numeric>
 #include <stdexcept>
 #include <string>
 
 using namespace std;
 
 class Rational {
 public:
     Rational() = default;
 
     Rational(int value)
         : numerator_(value)
         , denominator_(1) {
     }
 
     Rational(int numerator, int denominator)
         : numerator_(numerator)
         , denominator_(denominator) {
             if(denominator == 0){
                 throw domain_error("Error");
             }
         Normalize();
     }
 
     int Numerator() const {
         return numerator_;
     }
 
     int Denominator() const {
         return denominator_;
     }
 
     Rational& operator+=(Rational right) {
         numerator_ = numerator_ * right.denominator_ + right.numerator_ * denominator_;
         denominator_ *= right.denominator_;
         Normalize();
         return *this;
     }
 
     Rational& operator-=(Rational right) {
         numerator_ = numerator_ * right.denominator_ - right.numerator_ * denominator_;
         denominator_ *= right.denominator_;
         Normalize();
         return *this;
     }
 
     Rational& operator*=(Rational right) {
         numerator_ *= right.numerator_;
         denominator_ *= right.denominator_;
         Normalize();
         return *this;
     }
 
     Rational& operator/=(Rational right) {
         if (right.numerator_ == 0) {
             throw invalid_argument("Division by zero");
         }
         numerator_ *= right.denominator_;
         denominator_ *= right.numerator_;
         Normalize();
         return *this;
     }
 
 private:
     void Normalize() {
         if (denominator_ < 0) {
             numerator_ = -numerator_;
             denominator_ = -denominator_;
         }
         int n = gcd(numerator_, denominator_);
         numerator_ /= n;
         denominator_ /= n;
     }
 
     int numerator_ = 0;
     int denominator_ = 1;
 };
 
 ostream& operator<<(ostream& output, Rational rational) {
     return output << rational.Numerator() << '/' << rational.Denominator();
 }
 
 istream& operator>>(istream& input, Rational& rational) {
     int numerator;
     int denominator;
     char slash;
     if ((input >> numerator) && (input >> slash) && (slash == '/') && (input >> denominator)) {
         rational = Rational{numerator, denominator};
     }
     return input;
 }
 
 Rational operator+(Rational value) {
     return value;
 }
 
 Rational operator-(Rational value) {
     return {-value.Numerator(), value.Denominator()};
 }
 
 Rational operator+(Rational left, Rational right) {
     return left += right;
 }
 
 Rational operator-(Rational left, Rational right) {
     return left -= right;
 }
 
 Rational operator*(Rational left, Rational right) {
     return left *= right;
 }
 
 Rational operator/(Rational left, Rational right) {
     return left /= right;
 }
 
 bool operator==(Rational left, Rational right) {
     return left.Numerator() == right.Numerator() && left.Denominator() == right.Denominator();
 }
 
 bool operator!=(Rational left, Rational right) {
     return !(left == right);
 }
 
 bool operator<(Rational left, Rational right) {
     return left.Numerator() * right.Denominator() < left.Denominator() * right.Numerator();
 }
 
 bool operator>(Rational left, Rational right) {
     return left.Numerator() * right.Denominator() > left.Denominator() * right.Numerator();
 }
 
 bool operator>=(Rational left, Rational right) {
     return !(left < right);
 }
 
 bool operator<=(Rational left, Rational right) {
     return !(left > right);
 }
 
 // ========== для примера ========
 
 int main() {
     try {
         // При попытке сконструировать дробь с нулевым знаменателем
         // должно выброситься исключение domain_error
         const Rational invalid_value{1, 0};
         // Следующая строка не должна выполниться
         cout << invalid_value << endl;
     } catch (const domain_error& e) {
         cout << "Ошибка: "s << e.what() << endl;
     }
 }