Function Adaptor
Function adaptor used to reverse the sense of a unary predicate function object.
#include <functional>
template<class Predicate> unary_negate <Predicate> not1 (const Predicate&);
not1 is a function adaptor, known as a negator, that takes a unary predicate function object as its argument and returns a unary predicate function object that is the complement of the original. unary_negate is a function object class that provides a return type for the not1 negator.
Note that not1 works only with function objects that are defined as subclasses of the class unary_function.
Negators, not2, unary_function, unary_negate, pointer_to_unary_function