negator.cpp

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#include <functional>   // for unary_function
#include <ios>          // for boolalpha
#include <iostream>     // for cout, endl
 
#include <examples.h>
 
 
// Create a new predicate from unary_function.
template <class Arg>
struct is_odd : public std::unary_function<Arg, bool>
{
    bool operator() (const Arg &arg1) const {
        return arg1 % 2 != 0;
    }
};
 
 
int main ()
{
    std::less<int> less_func;
 
    // Use not2 on less.
    std::cout << std::boolalpha
              << less_func (1, 4) << '\n'
              << less_func (4, 1) << '\n'
              << std::not2 (std::less<int>())(1, 4) << '\n'
              << std::not2 (std::less<int>())(4, 1) << '\n';
 
    // Create an instance of our predicate.
    is_odd<int> odd;
 
    // Use not1 on our user defined predicate.
    std::cout << odd (1) << '\n'
              << odd (4) << '\n'
              << std::not1 (odd)(1) << '\n'
              << std::not1 (odd)(4) << std::endl;
 
    return 0;
}