std::shared_ptr: reset() vs. assignment

Question

This is a basic question, but I did not find a previous post about it. The title of the following question sounds like it might be the same question as mine, but the question it

Answer 1

reset() changes the managed object of an existing shared_ptr.

p = std::shared_ptr(new int(5)); and p.reset(new int(5));

The former involves creating a new shared_ptr and moving it into a variable. The latter does not create a new object, it simply changes the underlying pointer in managed by the shared_ptr.

Put another way the two are meant to be used in different cases. Assignment is for when you have a shared_ptr and reset for when you have a raw pointer.

Another thing to keep in mind is that shared_ptr was available in boost before move assignment existed and influenced the latest version heavily. Without move assignment being able to change a shared_ptr without making a copy is beneficial as it saves you the bookkeeping of the extra object.