std::get_deleter
template< class Deleter, class T > Deleter* get_deleter( const std::shared_ptr<T>& p ); | ? | (since C++11) |
|---|
访问p%27s缺失。如果共享指针p拥有cv-不合格类型的删除器。Deleter%28等。如果它是用一个以删除器作为参数%29的构造函数创建的，那么返回一个指向删除器的指针。否则，返回空指针。
参数
p | - | a shared pointer whose deleter needs to be accessed |
|---|
返回值
指向所拥有的删除项的指针或nullptr返回的指针至少在至少一个仍然有效。shared_ptr比如拥有它的人。
例外
noexcept规格：
noexcept
注记
返回的指针可能比最后一个指针更长。shared_ptr例如，如果std::weak_ptrS保持不变，实现%27T销毁删除器，直到整个控制块被销毁。
例
演示共享[医]ptr删除项独立于共享[医]PTR%27S型。
二次
#include <iostream>
#include <memory>
struct Foo { int i; };
void foo_deleter(Foo * p)
{
std::cout << "foo_deleter called!\n";
delete p;
}
int main()
{
std::shared_ptr<int> aptr;
{
// create a shared_ptr that owns a Foo and a deleter
auto foo_p = new Foo;
std::shared_ptr<Foo> r(foo_p, foo_deleter);
aptr = std::shared_ptr<int>(r, &r->i); // aliasing ctor
// aptr is now pointing to an int, but managing the whole Foo
} // r gets destroyed (deleter not called)
// obtain pointer to the deleter:
if(auto del_p = std::get_deleter<void(*)(Foo*)>(aptr))
{
std::cout << "shared_ptr<int> owns a deleter\n";
if(*del_p == foo_deleter)
std::cout << "...and it equals &foo_deleter\n";
} else
std::cout << "The deleter of shared_ptr<int> is null!\n";
} // deleter called here二次
产出：
二次
shared_ptr<int> owns a deleter
...and it equals &foo_deleter
foo_deleter called!二次
另见
(constructor) | std::shared_ptr constructors (public member function) |
|---|
? 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
