std::pointer_to_unary_function
Min standard notice:
std::pointer_to_unary_function is a function object that acts as a wrapper around a unary function.
# Declarations
template<
class Arg,
class Result
> class pointer_to_unary_function : public std::unary_function<Arg, Result>;
(deprecated in C++11) (removed in C++17)
# Parameters
f: pointer to a function to store
# Return value
The value returned by the called function.