What will be returned from std::set.end() exactly in c++?

Question

When you refers to cppreference, you will find this:

Returns an iterator to the element following the last element of the container. This element acts as a placeholder; attempting to access it results in undefined behavior.

Then I run the following code:

std::set<int> s {1, 2, 3};
cout << *s.end() << endl;

The out put is: 3, why?

undefined behavior means anything can happen. Including three. — aschepler, Mar 08 '17 at 01:49
Undefined behaviour that looks like it "works" is the most insidious kind. — user4581301, Mar 08 '17 at 01:52
with visualc++ i get the following error: "map/set iterator not dereferencable" :) — r3bel, Mar 08 '17 at 01:54

score 6 · Accepted Answer · answered Mar 08 '17 at 01:49

What will be returned from std::set.end() exactly in c++?

It returns:

an iterator to the element following the last element of the container.

Note that:

This element acts as a placeholder; attempting to access it results in undefined behavior.

The out put is: 3, why?

Because:

attempting to access it results in undefined behavior.

so it can do anything your compiler feels like doing, and returning 3 is a kind of anything, that your compiler apparently felt like doing.

@cong I mean, you *did* have most of the information right in front of you already... — user253751, Mar 08 '17 at 02:02

What will be returned from std::set.end() exactly in c++?

1 Answers1