The following code example is taken from the book
The C++ Standard Library - A Tutorial and Reference, 2nd Edition
by Nicolai M. Josuttis, Addison Wesley Longman, 2012
Copyright © 2012 by Pearson Education, Inc. and Nicolai M. Josuttis
#include <iostream>
template <typename charT, typename traits>
inline
std::basic_istream<charT,traits>&
operator >> (std::basic_istream<charT,traits>& strm, Fraction& f)
{
int n, d;
// read value of numerator
strm >> n;
// if available
// - read '/' and value of demonimator
if (strm.peek() == '/') {
strm.ignore();
strm >> d;
}
else {
d = 1;
}
// if denominator is zero
// - set failbit as I/O format error
if (d == 0) {
strm.setstate(std::ios::failbit);
return strm;
}
// if everything is fine so far
// - change the value of the fraction
if (strm) {
f = Fraction(n,d);
}
return strm;
}