std::unary_negate
| Defined in header
<functional>
|
||
| template< class Predicate >
struct unary_negate : public std::unary_function<Predicate::argument_type, bool>; |
(until C++11) | |
| template< class Predicate >
struct unary_negate; |
(since C++11) | |
unary_negate is a wrapper function object returning the complement of the unary predicate it holds.
The unary predicate type must define a member type, argument_type, that is convertible to the predicate's parameter type. The unary function objects obtained from std::ref, std::cref, std::negate, std::logical_not, std::mem_fn, std::function, std::hash, or from another call to std::not1 have this type defined, as are function objects derived from the deprecated std::unary_function.
unary_negate objects are easily constructed with helper function std::not1.
Contents |
[edit] Member types
| Type | Definition |
argument_type
|
Predicate::argument_type |
result_type
|
bool |
[edit] Member functions
| (constructor) |
constructs a new unary_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::unary_negate::unary_negate
| explicit unary_negate( Predicate const& pred );
|
||
Constructs a unary_negate function object with the stored predicate pred.
Parameters
| pred | - | predicate function object |
std::unary_negate::operator()
| bool operator()( argument_type const& x ) const;
|
||
Returns the logical complement of the result of calling pred(x).
Parameters
| x | - | argument to pass through to predicate |
Return value
The logical complement of the result of calling pred(x).
[edit] Example
#include <algorithm> #include <functional> #include <iostream> #include <vector> struct less_than_7 : std::unary_function<int, bool> { bool operator()(int i) const { return i < 7; } }; int main() { std::vector<int> v; for (int i = 0; i < 10; ++i) v.push_back(i); std::unary_negate<less_than_7> not_less_than_7((less_than_7())); std::cout << std::count_if(v.begin(), v.end(), not_less_than_7); /* C++11 solution: // Use std::function<bool (int)> std::function<bool (int)> not_less_than_7 = [](int x)->bool{ return !less_than_7()(x); }; std::cout << std::count_if(v.begin(), v.end(), not_less_than_7); */ }
Output:
3
[edit] See also
| wrapper function object returning the complement of the binary predicate it holds (class template) |
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| (C++11)
|
wraps callable object of any type with specified function call signature (class template) |
| constructs custom std::unary_negate object (function template) |
|
| (deprecated)
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creates an adaptor-compatible function object wrapper from a pointer to function (function template) |
| (deprecated)
|
adaptor-compatible unary function base class (class template) |