std::swap(std::shared_ptr)

 

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std::shared_ptr

成員函式

shared_ptr::shared_ptr

shared_ptr::~shared_ptr

shared_ptr::operator=

修改器

shared_ptr::reset

shared_ptr::swap

觀察器

shared_ptr::get

shared_ptr::operator*shared_ptr::operator->

shared_ptr::operator[] (C++17)

shared_ptr::use_count

shared_ptr::unique (C++20之前已棄用，C++20中移除*)

shared_ptr::operator bool

shared_ptr::owner_before

shared_ptr::owner_hash (C++26)

shared_ptr::owner_equal (C++26)

非成員函式

swap(std::shared_ptr)

make_sharedmake_shared_for_overwrite (C++20 起)

allocate_sharedallocate_shared_for_overwrite (C++20 起)

static_pointer_castdynamic_pointer_castconst_pointer_castreinterpret_pointer_cast (C++17)

get_deleter

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

operator<<

atomic_xxx 函式 (C++20中已棄用，C++26中移除*)

輔助類

atomic<std::shared_ptr> (C++20)

hash<std::shared_ptr>

推導指南(C++17)

 

定義於標頭檔案 <memory>
template< class T > void swap( std::shared_ptr<T>& lhs, std::shared_ptr<T>& rhs ) noexcept;		(C++11 起)

特化 std::shared_ptr 的 std::swap 演算法。交換 lhs 和 rhs 的內容。呼叫 lhs.swap(rhs)。

引數

lhs, rhs

-

要交換內容的智慧指標

返回值

(無)

複雜度

常數時間。

示例

執行此程式碼

#include <iostream>
#include <memory>
#include <string>
 
struct Foo {
    Foo(int _val) : val(_val) { std::cout << "Foo...\n"; }
    ~Foo() { std::cout << "~Foo...\n"; }
    std::string print() { return std::to_string(val); }
    int val;
};
 
int main()
{
    std::shared_ptr<Foo> p1 = std::make_shared<Foo>(100);
    std::shared_ptr<Foo> p2 = std::make_shared<Foo>(200);
    auto print = [&]() {
        std::cout << " p1=" << (p1 ? p1->print() : "nullptr");
        std::cout << " p2=" << (p2 ? p2->print() : "nullptr") << '\n';  
    };
    print();
 
    std::swap(p1, p2);
    print();
 
    p1.reset();
    print();
 
    std::swap(p1, p2);
    print();   
}

輸出

Foo...
Foo...
 p1=100 p2=200
 p1=200 p2=100
~Foo...
 p1=nullptr p2=100
 p1=100 p2=nullptr
~Foo...

參閱

swap	交換兩個物件的值 (函式模板)
swap	交換內容 (public 成員函式)