The following code example is taken from the book
The C++ Standard Library - A Tutorial and Reference
by Nicolai M. Josuttis, Addison-Wesley, 1999
© Copyright Nicolai M. Josuttis 1999
#include <iostream>
inline
std::ostream& operator << (std::ostream& strm, const Fraction& f)
{
strm << f.numerator() << '/' << f.denominator();
return strm;
}