Ostream operator overloading

[tonyg362]

Trying to write my own complex number class, when I overload the << operator as below, it compiles fine when I don't try to use the << operator, but when I try to use the operator in main I get this error in VS 2009:

1>------ Build started: Project: complex, Configuration: Debug Win32 ------
1>Compiling...
1>main.cpp
1>Linking...
1>main.obj : error LNK2019: unresolved external symbol "class std::basic_ostream<char,struct std::char_traits<char> > & __cdecl operator<<(class std::basic_ostream<char,struct std::char_traits<char> > &,class complex<int> const &)" (??6@YAAAV?$basic_ostream@DU?$char_traits@D@std@@@std@@AAV01@ABV?$complex@H@@@Z) referenced in function _main

Any ideas?

template<typename T>
class complex{
  public:
    //constructors etc.
    friend std::ostream& operator<<(ostream&, const complex<T>&);

  private:
    T Re, Im;
};

template<typename T>
std::ostream& operator<<(std::ostream &out, const complex<T> &rhs){
  out << (double)rhs.Re << " " << (double)rhs.Im;

  return out;
}

int main(){
  complex num(3,4);

  cout << num << endl;

  return 0;
}

[firedraco]

You don't seem to be including iostream.

[tonyg362]

I didn't think it was necessary to show that in this post, but in the actual code I am including iostream.

[helios]

The function you're declaring on line 5 is not templated. Add template <typename T2> before it, and change <T> to <T2>.

[tonyg362]

Wow stupid mistake, thanks.