std::shared_ptr<T>::get

声明

直到 C++17

T* get() const noexcept;

自 C++17 起

element_type* get() const noexcept;

返回存储的指针。

参数

(无)

返回值

存储的指针。

备注

shared_ptr 可能在拥有对象的同时存储指向另一个对象的指针。get() 返回存储的指针，而不是被管理的指针。

示例

#include <iostream>
#include <memory>
#include <string_view>
 
int main()
{
    auto output = [](std::string_view msg, int const* pInt) {
        std::cout 
        << msg << *pInt 
        << " in " << pInt 
        << "\n";
    };
 
    int* pInt = new int(42);
    std::shared_ptr<int> pShared = std::make_shared<int>(42);
 
    output("Naked pointer ", pInt);
//  output("Shared pointer ", pShared); // compiler error
    output("Shared pointer with get() ", pShared.get());
 
    delete pInt;
 
 
    std::cout << "\nThe shared_ptr's aliasing constructor demo.\n";
    struct Base1 { int i1{}; };
    struct Base2 { int i2{}; };
    struct Derived : Base1, Base2 { int i3{}; };
 
    std::shared_ptr<Derived> p(new Derived());
    std::shared_ptr<Base2> q(p, static_cast<Base2*>(p.get()));
    std::cout 
        << "q shares ownership with p, but points to Base2 subobject:\n"
        << "p.get(): " << p.get() << '\n'
        << "q.get(): " << q.get() << '\n'
        << "&(p->i1): " << &(p->i1) << '\n'
        << "&(p->i2): " << &(p->i2) << '\n'
        << "&(p->i3): " << &(p->i3) << '\n'
        << "&(q->i2): " << &(q->i2) << '\n';
}

可能结果

Naked pointer 42 in 0xacac20
Shared pointer with get() 42 in 0xacac50
 
The shared_ptr's aliasing constructor demo.
q shares ownership with p, but points to Base2 subobject:
p.get(): 0xacac20
q.get(): 0xacac24
&(p->i1): 0xacac20
&(p->i2): 0xacac24
&(p->i3): 0xacac28
&(q->i2): 0xacac24