gistfile1.hpp

class WellBehavedFunctor : public unary_functor<int, bool>
{
public:
    bool operator()(int i) { return i < 3; }
}

std::vector<int> numbers;

// Prints the number of numbers in the numbers vector that are 3 or greater.
std::cout << std::count_if(numbers.begin(), numbers.end(), std::not1(WellBehavedFunctor()));