binary_negate Class

Article
01/02/2018

The latest version of this topic can be found at binary_negate Class.

A template class providing a member function that negates the return value of a specified binary function.

Syntax

template <class Operation>  
class binary_negate       : public binary_function <typename Operation::first_argument_type, typename Operation::second_argument_type, bool>     {    public:    explicit binary_negate(const Operation& _Func);

    bool operator()(const typename Operation::first_argument_type& left, const typename Operation::second_argument_type& right) const;

 };

Parameters

_Func
The binary function to be negated.

left
The left operand of the binary function to be negated.

right
The right operand of the binary function to be negated.

Return Value

The negation of the binary function.

Remarks

The template class stores a copy of a binary function object _ Func. It defines its member function operator() as returning !_ Func(left, right).

The constructor of binary_negate is rarely used directly. The helper function not2 is usually preferred to declare and use the binary_negator adaptor predicate.

Example

// functional_binary_negate.cpp  
// compile with: /EHsc  
#define _CRT_RAND_S  
#include <stdlib.h>  
  
#include <vector>  
#include <algorithm>  
#include <functional>  
#include <iostream>  
  
int main( )  
{  
   using namespace std;  
   vector <unsigned int> v1;  
   vector <unsigned int>::iterator Iter1;  
  
   unsigned int i;  
   v1.push_back( 6262 );  
   v1.push_back( 6262 );  
   unsigned int randVal = 0;  
   for ( i = 0 ; i < 5 ; i++ )  
   {  
      rand_s(&randVal);  
      v1.push_back( randVal );  
   }  
  
   cout << "Original vector v1 = ( " ;  
   for ( Iter1 = v1.begin( ) ; Iter1 != v1.end( ) ; Iter1++ )  
      cout << *Iter1 << " ";  
   cout << ")" << endl;  
  
   // To sort in ascending order,  
   // use default binary predicate less<unsigned int>( )  
   sort( v1.begin( ), v1.end( ) );  
   cout << "Sorted vector v1 = ( " ;  
   for ( Iter1 = v1.begin( ) ; Iter1 != v1.end( ) ; Iter1++ )  
      cout << *Iter1 << " ";  
   cout << ")" << endl;  
  
   // To sort in descending order,  
   // use the binary_negate function  
   sort( v1.begin( ), v1.end( ),  
   binary_negate<less<unsigned int> >(less<unsigned int>( ) ) );  
  
   // The helper function not2 could also have been used  
   // in the above line and is usually preferred for convenience  
   // sort( v1.begin( ), v1.end( ), not2(less<unsigned int>( ) ) );  
  
   cout << "Resorted vector v1 = ( " ;  
   for ( Iter1 = v1.begin( ) ; Iter1 != v1.end( ) ; Iter1++ )  
      cout << *Iter1 << " ";  
   cout << ")" << endl;  
}  
\* Output:   
Original vector v1 = ( 6262 6262 2233879413 2621500314 580942933 3715465425 3739828298 )  
Sorted vector v1 = ( 6262 6262 580942933 2233879413 2621500314 3715465425 3739828298 )  
Resorted vector v1 = ( 3739828298 3715465425 2621500314 2233879413 580942933 6262 6262 )  
*\

Requirements

Header: <functional>

std

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