binary_negate

template <class Predicate> class binary_negate
  : public binary_function <typename Predicate::first_argument_type,
                            typename Predicate::second_argument_type, bool>
{
protected:
  Predicate fn;
public:
  explicit binary_negate ( const Predicate& pred ) : fn (pred) {}
  bool operator() (const typename Predicate::first_argument_type& x,
                   const typename Predicate::second_argument_type& y) const
  { return !fn(x,y); }
};

// binary_negate example
#include <iostream>
#include <functional>
#include <algorithm>
using namespace std;
int main () {
  equal_to<int> equality;
  binary_negate < equal_to<int> > nonequality (equality);
  int foo[] = {10,20,30,40,50};
  int bar[] = {0,15,30,45,60};
  pair<int*,int*> firstmatch,firstmismatch;
  firstmismatch=mismatch (foo,foo+5,bar,equality);
  firstmatch=mismatch (foo,foo+5,bar,nonequality);
  cout << "First mismatch in bar is " << *firstmismatch.second << "\n";
  cout << "First match in bar is " << *firstmatch.second << "\n";
  return 0;
}