Question

I’m trying to add in an optional parameter in a template function… Basically a parameter that overloads the relational operator depending on the user’s type. It’s my first template funct so I’m pretty basic. This should sort through a vector of the user’s type and return the greatest element. Something like:

template <typename Type>
Type FindMax(std::vector<Type> vec, RelationalOverloadHere)
/..../

What would the second “optional” parameter look like?

Answer 1

Usually this is like

template<typename Type, typename BinaryOperation = std::less<Type> >
Type FindMax(const std::vector<Type>& vec, BinaryOperation op = BinaryOperation());

So the standard comparator is <, but can be customized if desired.

In the standard library, the respective algorithm is max_element with the following overload:

template<typename ForwardIterator, typename Compare>
  ForwardIterator
  max_element(ForwardIterator first, ForwardIterator last, Compare comp);