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) (deprecated in C++17) |
unary_negate是一个包装函数对象，返回它所持有的一元谓词的补码。
一元谓词类型必须定义成员类型，argument_type，它可转换为谓词%27s参数类型。获取的一元函数对象。std::ref，，，std::cref，，，std::negate，，，std::logical_not，，，std::mem_fn，，，std::function，，，std::hash，或者从另一个电话到std::not1定义此类型，就像从已弃用的函数对象派生的函数对象一样。std::unary_function...
unary_negate对象很容易用助手函数构造。std::not1...
成员类型
Type | Definition |
|---|---|
argument_type | Predicate::argument_type |
result_type | bool |
成员函数
(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) |
性病：一元[医]否定：：一元[医]否定
explicit unary_negate( Predicate const& pred ); | | (until C++14) |
|---|---|---|
explicit constexpr unary_negate( Predicate const& pred ); | | (since C++14) |
构造一个unary_negate具有存储谓词的函数对象。pred...
参数
pred | - | predicate function object |
|---|
性病：一元[医]否定：：操作员%28%29
bool operator()( argument_type const& x ) const; | | (until C++14) |
|---|---|---|
constexpr bool operator()( argument_type const& x ) const; | | (since C++14) |
返回调用结果的逻辑补码。pred(x)...
参数
x | - | argument to pass through to predicate |
|---|
返回值
调用结果的逻辑补充pred(x)...
例
二次
#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);
*/
}二次
产出：
二次
3二次
另见
binary_negate (deprecated) | wrapper function object returning the complement of the binary predicate it holds (class template) |
|---|---|
function (C++11) | wraps callable object of any type with specified function call signature (class template) |
not1 (deprecated) | constructs custom std::unary_negate object (function template) |
ptr_fun (until C++17) | creates an adaptor-compatible function object wrapper from a pointer to function (function template) |
unary_function (until C++17) | adaptor-compatible unary function base class (class template) |
© cppreference.com在CreativeCommonsAttribution下授权-ShareAlike未移植许可v3.0。
本文档系腾讯云开发者社区成员共同维护，如有问题请联系 cloudcommunity@tencent.com
