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std::binary_negate(3) C++ Standard Libary std::binary_negate(3) NAME std::binary_negate - std::binary_negate Synopsis Defined in header <functional> template< class Predicate > struct binary_negate : public std::binary_function< Predicate::first_argument_type, (until C++11) Predicate::second_argument_type, bool >; template< class Predicate > (since C++11) struct binary_negate; (deprecated in C++17) (removed in C++20) std::binary_negate is a wrapper function object returning the com- plement of the binary predicate it holds. The binary predicate type must define two member types, first_argu- ment_type and second_argument_type, that are convertible to the predicate's para- meter types. The function objects obtained from std::owner_less, std::ref, std::cref, std::plus, std::minus, std::multiplies, std::divides, std::modulus, std::equal_to, std::not_equal_to, std::greater, std::less, std::greater_equal, std::less_equal, std::logical_not, std::logical_or, std::bit_and, std::bit_or, std::bit_xor, std::mem_fn, std::map::value_comp, std::multimap::value_comp, std::function, or from a call to std::not2 have these types defined, as are function ob- jects derived from the deprecated std::binary_function. std::binary_negate objects are easily constructed with helper func- tion std::not2. Member types Type Definition first_argument_type Predicate::first_argument_type second_argument_type Predicate::second_argument_type result_type bool Member functions constructor constructs a new binary_negate object with the sup- plied predicate (public member function) returns the logical complement of the result of a call to the stored operator() predicate (public member function) std::binary_negate::binary_negate explicit binary_negate( Predicate const& pred ); (until C++14) constexpr explicit binary_negate( Predicate const& pred ); (since C++14) Constructs a std::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, (until C++14) second_argument_type const& y ) const; constexpr bool operator()( first_argument_type const& x, (since C++14) 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). Example // Run this code #include <algorithm> #include <cstddef> #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; for (int i = 0; i < 7; ++i) v1.push_back(i); std::vector<int> v2(v1.size()); std::reverse_copy(v1.begin(), v1.end(), v2.begin()); std::vector<bool> v3(v1.size()); std::binary_negate<same> not_same((same())); // C++11 solution: // 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 (std::size_t i = 0; i != v1.size(); ++i) std::cout << v1[i] << " != " << v2[i] << " : " << v3[i] << '\n'; } Output: 0 != 6 : true 1 != 5 : true 2 != 4 : true 3 != 3 : false 4 != 2 : true 5 != 1 : true 6 != 0 : true See also binary_function adaptor-compatible binary function base class (deprecated in C++11) (class template) (removed in C++17) function wraps callable object of any copy con- structible type with (C++11) specified function call signature (class template) move_only_function wraps callable object of any type with speci- fied function call (C++23) signature (class template) not2 constructs custom std::binary_negate object (deprecated in C++17) (function template) (removed in C++20) ptr_fun creates an adaptor-compatible function object wrapper from a (deprecated in C++11) pointer to function (removed in C++17) (function template) unary_negate wrapper function object returning the comple- ment of the unary (deprecated in C++17) predicate it holds (removed in C++20) (class template) http://cppreference.com 2024.06.10 std::binary_negate(3)
NAME | Synopsis | Member types | Member functions | Parameters | Parameters | Return value | Example | Output: | See also
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