c++ - template class + operators + friends = unresolved externals -

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i have class called fraction, , i'm declaring operators friends. declared friend operators beforehand, http://www.parashift.com/c++-faq-lite/templates.html#faq-35.16 told me do, fixed +, -, *, , /. << , >> still don't work.

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);

and class:

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; }

as "dark_charlie" says, remove const.

i'd rather have made comment, unfortunately stackoverflow not yet allow me comment (to person feeling urge comment shouldn't make comment: it's aimed @ you).


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