CODEWITHSUNDEEP
c++linuxiterator
ProMike
ProMike

Reputation: 129

The difference in behaviour of VS2022 and g++14 compilers

It's the assignment from student work, the task was to write sort using std::nth_element and iterators. I've done this:

template <typename It> void quick_sort(It beg, It end)
{
    if (beg == end || std::distance(beg, end) == 1) return;
    auto dist = std::distance(beg, end) / 2;
    std::nth_element(beg, std::next(beg, dist), end);
}

And it worked only on some inputs. Then I asked a mate about his implementation. And apart that he used one explicit variable to store distance, it was just the same. To be sure I copied his code but nothing changed. I've read that "Elements are hypothetically sorted with respect to operator<(until C++20)". But for all the people using VS it works and as I'm the only using Linux, so have nobody else to check. To do as much as I can, I tried clang18, but it resulted the same issue. Points for that task now are gone, as I was said at the beginning of the semester to use Windows as all the others, but I just want to know why the things are like this. Main is:

int main()
{
std::vector<int> v{2, 5, 6, 1, 7, 0};
std::vector<int> v_sorted{0, 1, 2, 5, 6, 7};
quick_sort(v.begin(), v.end());
assert(v == v_sorted);

As I see, the border pairs for some input are not sorted.

To add to changing compilers I've also tried to change the second argument for nth_element to random iterator in range argument vector, nothing changed.

Upvotes: 0

Views: 50

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