NAME¶

std::shared_ptr::~shared_ptr - std::shared_ptr::~shared_ptr

Synopsis¶

~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¶

// Run this code

#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"
}

Output:¶

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()

See also¶

destructor destroys a weak_ptr
(public member function of std::weak_ptr<T>)