std:: unary_negate
|
|
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
|
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
|
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Old binders and adaptors | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
|
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
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)
(deprecated in C++17) (removed in C++20) |
|
std::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
.
std::unary_negate
objects are easily constructed with helper function
std::not1
.
Member types
| Type | Definition |
argument_type
|
Predicate :: argument_type |
result_type
|
bool |
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
)
;
|
(until C++14) | |
|
constexpr
explicit
unary_negate
(
Predicate
const
&
pred
)
;
|
(since C++14) | |
Constructs a
std::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
;
|
(until C++14) | |
|
constexpr
bool
operator
(
)
(
argument_type
const
&
x
)
const
;
|
(since C++14) | |
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 ) .
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(7, 7); v[0] = v[1] = v[2] = 6; std::unary_negate<less_than_7> not_less_than_7((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:
4
See also
|
(deprecated in C++17)
(removed in C++20)
|
wrapper function object returning the complement of the binary predicate it holds
(class template) |
|
(C++11)
|
copyable wrapper of any copy constructible callable object
(class template) |
|
(C++23)
|
move-only wrapper of any callable object that supports qualifiers in a given call signature
(class template) |
|
(deprecated in C++17)
(removed in C++20)
|
constructs custom
std::unary_negate
object
(function template) |
|
(deprecated in C++11)
(removed in C++17)
|
creates an adaptor-compatible function object wrapper from a pointer to function
(function template) |
|
(deprecated in C++11)
(removed in C++17)
|
adaptor-compatible unary function base class
(class template) |