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Defined in header `<functional>`

template< class Predicate > struct binary_negate : public std::binary_function< Predicate::first_argument_type, Predicate::second_argument_type, bool >;		(until C++11)

template< class Predicate > struct binary_negate;		(since C++11)

binary_negate is a wrapper function object returning the complement of the binary predicate it holds.

The binary predicate type must define two subtypes, first_argument_type and second_argument_type, that is convertible to the predicate's two parameter types. Binary function objects derived from std::binary_function will have these types defined, as will functions wrapped in a call to std::ptr_fun. In C++11, a std::function specialization for binary functions provides these types.

binary_negate objects are easily constructed with helper function std::not2.

std::binary_negate::binary_negate


explicit binary_negate( Predicate const& pred );

Constructs a binary_negate function object with the stored predicate pred.

Parameters

pred

-

predicate function object

std::binary_negate::operator()


bool operator()( first_argument_type const& x, second_argument_type const& y ) const;

Returns the logical complement of the result of calling pred(x, y).

Parameters

x	-	first argument to pass through to predicate
y	-	second argument to pass through to predicate

Return value

The logical complement of the result of calling pred(x, y).

[edit] Example

#include <algorithm>
#include <functional>
#include <iostream>
#include <vector>
 
struct same : std::binary_function<int, int, bool>
{
    bool operator()(int a, int b) const { return a == b; }
};
 
int main()
{
    std::vector<int> v1;
    std::vector<int> v2;
    for (int i = 0; i < 10; ++i) v1.push_back(i);
    for (int i = 0; i < 10; ++i) v2.push_back(10 - i);
 
    std::vector<bool> v3(v1.size());
 
    std::binary_negate<same> not_same((same()));
 
    std::transform(v1.begin(), v1.end(), v2.begin(), v3.begin(), not_same);
 
    /* C++11 solution:
        // Use std::function<bool (int, int)>
        std::function<bool (int, int)> not_same =
            [](int x, int y)->bool{ return !same()(x, y); };
 
        std::transform(v1.begin(), v1.end(), v2.begin(), v3.begin(), not_same);
    */
 
    std::cout.setf(std::ios_base::boolalpha);
    for (int i = 0; i < 10; ++i)
        std::cout << v1[i] << ' ' << v2[i] << ' ' << v3[i] << '\n';
}

Output:

0 10 true
1 9 true
2 8 true
3 7 true
4 6 true
5 5 false
6 4 true
7 3 true
8 2 true
9 1 true

[edit] See also


binary_function (deprecated)	adaptor-compatible binary function base class (class template)

function (C++11)	wraps callable object of any type with specified function call signature (class template)

not2	constructs custom std::binary_negate object (function template)

ptr_fun (deprecated)	creates an adaptor-compatible function object wrapper from a pointer to function (function template)

unary_negate	wrapper function object returning the complement of the unary predicate it holds (class template)


(constructor)	constructs a new binary_negate object with the supplied predicate (public member function)

operator()	returns the logical complement of the result of a call to the stored predicate (public member function)

std::binary_negate

From Cppreference

Contents

[edit] Member types

[edit] Member functions

std::binary_negate::binary_negate

Parameters

std::binary_negate::operator()

Parameters

Return value

[edit] Example

[edit] See also


Type	Definition

`first_argument_type`	Predicate::first_argument_type

`second_argument_type`	Predicate::second_argument_type

`result_type`	bool