std::flat_multimap<Key,T,Compare,KeyContainer,MappedContainer>:: contains
From cppreference.net
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flat multimap
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(C++26)
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(C++23)
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(C++23)
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(C++23)
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(C++23)
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std::flat_multimap
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bool
contains
(
const
Key
&
key
)
const
;
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(1) |
(自 C++23 起)
(自 C++26 起为 constexpr) |
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template
<
class
K
>
bool contains ( const K & x ) const ; |
(2) |
(自 C++23 起)
(自 C++26 起为 constexpr) |
1)
检查容器中是否存在键与
key
等效的元素。
2)
检查是否存在与
x
比较等价的键的元素。
目录 |
参数
| key | - | 要搜索元素的键值 |
| x | - | 可与键进行透明比较的任意类型值 |
返回值
true 表示存在这样的元素，否则为 false 。
复杂度
与容器大小呈对数关系。
示例
运行此代码
#include <iostream> #include <flat_map> int main() { std::flat_multimap<int, char> example{{1, 'a'}, {2, 'b'}}; for (int x : {2, 5}) if (example.contains(x)) std::cout << x << ": Found\n"; else std::cout << x << ": Not found\n"; }
输出：
2: Found 5: Not found
参见
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查找具有特定键的元素
(公开成员函数) |
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| td> 返回匹配特定键的元素数量 | |
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返回匹配特定键的元素范围
(公开成员函数) |