weak_ptr::swap

交換兩個 weak_ptr 物件。

void swap(weak_ptr& wp);

參數

• wp
  交換的弱式指標。

備註

成員函式讓資源一開始指向 *this 後續要求的 wp和資源一開始指向 wp 後續要求的 *this。函式不會變更兩個資源的參考計數，並且不會擲回任何例外狀況。

範例

 

// std_tr1__memory__weak_ptr_swap.cpp 
// compile with: /EHsc 
#include <memory> 
#include <iostream> 
 
struct deleter 
    { 
    void operator()(int *p) 
        { 
        delete p; 
        } 
    }; 
 
int main() 
    { 
    std::shared_ptr<int> sp1(new int(5)); 
    std::shared_ptr<int> sp2(new int(10)); 
    std::cout << "*sp1 == " << *sp1 << std::endl; 
 
    sp1.swap(sp2); 
    std::cout << "*sp1 == " << *sp1 << std::endl; 
 
    swap(sp1, sp2); 
    std::cout << "*sp1 == " << *sp1 << std::endl; 
    std::cout << std::endl; 
 
    std::weak_ptr<int> wp1(sp1); 
    std::weak_ptr<int> wp2(sp2); 
    std::cout << "*wp1 == " << *wp1.lock() << std::endl; 
 
    wp1.swap(wp2); 
    std::cout << "*wp1 == " << *wp1.lock() << std::endl; 
 
    swap(wp1, wp2); 
    std::cout << "*wp1 == " << *wp1.lock() << std::endl; 
 
    return (0); 
    } 
 

需求

標題: <memory>

命名空間: std

請參閱

參考

weak_ptr Class

weak_ptr::operator=