std::hash<std::unique_ptr>

 

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std::unique_ptr

成员函数

unique_ptr::unique_ptr

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unique_ptr::operator=

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unique_ptr::swap

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非成员函数

make_uniquemake_unique_for_overwrite (C++14)(C++20)

operator==operator!=operator<operator>operator<=operator>=operator<=> (C++20 前)(C++20)

operator<< (C++20)

std::swap

std::hash

 

template<class T, class Deleter> struct hash<unique_ptr<T, Deleter>>;		(C++11 起)

std::hash 对 std::unique_ptr<T, Deleter> 的模板特化允许用户获得 std::unique_ptr<T, Deleter> 类型对象的散列值。

若启用 std::hash<typename std::unique_ptr<T,D>::pointer> ，则启用特化 std::hash<std::unique_ptr<T,D>> （见 std::hash ），否则禁用它。

启用时，对于给定的 std::unique_ptr<T, D> p ，此特化确保 std::hash<std::unique_ptr<T, D>>()(p) == std::hash<typename std::unique_ptr<T, D>::pointer>()(p.get()) 。

此特化的成员函数不保证为 noexcept ，因为指针可能是缀饰指针且其散列函数可能抛出。

示例

运行此代码

#include <iostream>
#include <memory>
#include <functional>
 
struct Foo {
    Foo() { std::cout << "Foo...\n"; }
    ~Foo() { std::cout << "~Foo...\n\n"; }
};
 
int main()
{
    Foo* foo = new Foo();
    std::unique_ptr<Foo> up(foo);
 
    std::cout << "hash(up):  " << std::hash<std::unique_ptr<Foo>>()(up) << '\n';
    std::cout << "hash(foo): " << std::hash<Foo*>()(foo) << '\n';
}

输出：

Foo...
hash(up):  3686401041
hash(foo): 3686401041
~Foo...

参阅

hash (C++11)

散列函数对象 (类模板)