std::erase_if (std::unordered_multiset)
来自cppreference.com
< cpp | container | unordered multiset
| 定义于头文件 <unordered_set>
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| template< class Key, class Hash, class KeyEqual, class Alloc, class Pred > typename std::unordered_multiset<Key,Hash,KeyEqual,Alloc>::size_type |
(C++20 起) | |
从容器中擦除所有满足谓词 pred 的元素。等价于
auto old_size = c.size(); for (auto i = c.begin(), last = c.end(); i != last; ) { if (pred(*i)) { i = c.erase(i); } else { ++i; } } return old_size - c.size();
参数
| c | - | 要从中擦除的元素 |
| pred | - | 若应该擦除元素则对它返回 true 的谓词 |
返回值
擦除的元素数。
复杂度
线性。
示例
运行此代码
#include <unordered_set> #include <iostream> template<typename Os, typename Container> inline Os& operator<<(Os& os, Container const& container) { os << "{ "; for (const auto& item : container) { os << item << ' '; } return os << "}"; } int main() { std::unordered_multiset data { 0, 1, 2, 3, 3, 4, 5, 5, 6, 6, 7 }; std::cout << "Original:\n" << data << '\n'; auto divisible_by_3 = [](auto const& x) { return (x % 3) == 0; }; const auto count = std::erase_if(data, divisible_by_3); std::cout << "Erase all items divisible by 3:\n" << data << '\n' << count << " items erased.\n"; }
输出：
Original:
{ 7 6 6 5 5 4 3 3 2 1 0 }
Erase all items divisible by 3:
{ 7 5 5 4 2 1 }
5 items erased.参阅
| 移除满足特定判别标准的元素 (函数模板) |