weak_ptr::lock
Obtains exclusive ownership of a resource.
shared_ptr<Ty> lock() const;
Remarks
The member function returns an empty shared_ptr object if *this has expired; otherwise it returns a shared_ptr Class<Ty> object that owns the resource that *this points to.
Example
// std_tr1__memory__weak_ptr_lock.cpp
// compile with: /EHsc
#include <memory>
#include <iostream>
struct deleter
{
void operator()(int *p)
{
delete p;
}
};
int main()
{
std::weak_ptr<int> wp;
{
std::shared_ptr<int> sp(new int(10));
wp = sp;
std::cout << "wp.expired() == " << std::boolalpha
<< wp.expired() << std::endl;
std::cout << "*wp.lock() == " << *wp.lock() << std::endl;
}
// check expired after sp is destroyed
std::cout << "wp.expired() == " << std::boolalpha
<< wp.expired() << std::endl;
std::cout << "(bool)wp.lock() == " << std::boolalpha
<< (bool)wp.lock() << std::endl;
return (0);
}
wp.expired() == false *wp.lock() == 10 wp.expired() == true (bool)wp.lock() == false
Requirements
Header: <memory>
Namespace: std