How can you dynamically allocate "n number of elements" to which a shared_ptr will point to?
I was able to create a static array that a shared pointer will point to, but I'd like the user to enter a number and then allocate n number of elements.
shared_ptr<int[10]> p = make_shared<int[10]>();
You should create that shared_ptr like that
std::shared_ptr<int> sp( new int[10], std::default_delete<int[]>() );
You must give other deleter to shared_ptr
You can't use std::make_shared, because that function gives only 1 parameter, for create pointer on array you must create deleter too.
Or you can use too (like in comments , with array or with vector, which has own deleter)
std::shared_ptr<std::array<int,6>> ptr(std::make_shared<std::array<int, 6>>(std::array<int, 6>()));
How get particular element? Like that
std::shared_ptr<int> sp(new int[10], std::default_delete<int[]>());
sp.get()[0] = 5;
std::cout << sp.get()[0] << std::endl;
The language currently lacks the ability to use make_shared to accomplish that. It is addressed in P0674. Pretty sure it's going to make its way into the language, though it won't be C++11.
The wording will allow you to say
auto p = std::make_shared<int[10]>()
or
auto p = std::make_shared<int[]>(10)
Until C++20 (or whenever the proposal gets officially standardized), you're stuck with using the new syntax as linked in 21koizyd's answer.
I think better for this problem is unique_ptr template.
int amount = 10;
std::unique_ptr<int[]> name(new int[amount]);
I found the form below is wrong.
std::shared_ptr<std::array<int,6>> ptr(std::make_shared<std::array<int, 6>>(std::array<int, 6>()));
It invokes two times destructor.
If your input is not native type such as int, it will lead to a crash.
One can try it.
std::shared_ptr<std::array<int,6>> ptr(std::make_shared<std::array<int, 6>>());
Maybe the claim above is correct?
Is there anyone know why it invokes two times of destructor?
any thoughts?
std::shared_ptr<std::vector<int>>?std::array<int, 10>instead ofint[10]