std::not2
| Defined in header <functional>
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| template< class Predicate > std::binary_negate<Predicate> not2(const Predicate& pred); |
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not2 is a helper function to create a function object that returns the complement of the binary predicate function passed. The function object created is of type std::binary_negate<Predicate>.
The binary predicate type must define two member types, first_argument_type and second_argument_type, that are convertible to the predicate's parameter 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, {{c|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 another call to std::not2 have these types defined, as are function objects derived from the deprecated std::binary_function.
Contents |
[edit] Parameters
| pred | - | unary predicate |
[edit] Return value
std::not2 returns an object of type std::binary_negate<Predicate>, constructed with pred.
[edit] Exceptions
None.
[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::transform(v1.begin(), v1.end(), v2.begin(), v3.begin(), std::not2(same())); /* C++11 solution: // Use std::function<bool (int, int)> to create or wrap the predicate type std::function<bool (int, int)> same = [](int x, int y){ return x == y; }; std::transform(v1.begin(), v1.end(), v2.begin(), v3.begin(), std::not2(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
| wrapper function object returning the complement of the binary predicate it holds (class template) | |
| (C++11) |
wraps callable object of any type with specified function call signature (class template) |
| constructs custom std::unary_negate object (function template) | |
| (deprecated) |
creates an adaptor-compatible function object wrapper from a pointer to function (function template) |
| (deprecated) |
adaptor-compatible binary function base class (class template) |
