std::shared_ptr<T>::~shared_ptr
~shared_ptr();
If *this
owns an object and it is the last shared_ptr
owning it, the object is destroyed through the owned deleter.
After the destruction, the smart pointers that shared ownership with *this
, if any, will report a use_count()
that is one less than its previous value.
Notes
Unlike std::unique_ptr
, the deleter of std::shared_ptr
is invoked even if the managed pointer is null
.
Example
#include <memory>
#include <iostream>
struct S {
S() { std::cout << "S::S()\n"; }
~S() { std::cout << "S::~S()\n"; }
struct Deleter {
void operator()(S* s) const {
std::cout << "S::Deleter()\n";
delete s;
}
};
};
int main()
{
auto sp = std::shared_ptr<S>{ new S, S::Deleter{} };
auto use_count = [&sp](char c) {
std::cout
<< c << ") use_count(): "
<< sp.use_count() << '\n';
};
use_count('A');
{
auto sp2 = sp;
use_count('B');
{
auto sp3 = sp;
use_count('C');
}
use_count('D');
}
use_count('E');
// sp.reset();
// use_count('F'); // would print "F) use_count(): 0"
}
Result
S::S()
A) use_count(): 1
B) use_count(): 2
C) use_count(): 3
D) use_count(): 2
E) use_count(): 1
S::Deleter()
S::~S()