我有一个名为分数的类,我将一些运算符声明为朋友。我事先声明了友元运算符,正如http://www.parashift.com/c++-faq-lite/templates.html#faq-35.16告诉我的那样,但它只修复了 +、-、* 和 /。<< 和 >> 仍然不起作用。
template <class T> class Fraction;
template <class T> Fraction<T> operator+ (Fraction<T> const& left, Fraction<T> const& right);
template <class T> Fraction<T> operator- (Fraction<T> const& left, Fraction<T> const& right);
template <class T> Fraction<T> operator* (Fraction<T> const& left, Fraction<T> const& right);
template <class T> Fraction<T> operator/ (Fraction<T> const& left, Fraction<T> const& right);
template <class T> ostream& operator<< (const ostream& output, Fraction<T> const& value);
template <class T> istream& operator>> (const ostream& input, Fraction<T> const& value);
和班级:
template <class T>
class Fraction
{
...
friend Fraction<T> operator+ <>(const Fraction<T>& left, const Fraction<T>& right);
friend Fraction<T> operator- <>(const Fraction<T>& left, const Fraction<T>& right);
friend Fraction<T> operator* <>(const Fraction<T>& left, const Fraction<T>& right);
friend Fraction<T> operator/ <>(const Fraction<T>& left, const Fraction<T>& right);
friend ostream& operator<< <>(const ostream& output, const Fraction<T> value);
friend istream& operator>> <>(const istream& input, Fraction<T> value);
}
template <class T> ostream& operator<< <>(const ostream& output, const Fraction<T>& value)
{
output << value.Numerator << '/' << value.Denominator;
return output;
}
template <class T> istream& operator>> <>(const istream& input, Fraction<T>& value)
{
T n, d, char seperator;
cin >> n >> seperator >> d;
value.SetNumerator(n);
value.SetDenominator(d);
return input;
}