Does C++11 support variable sized arrays?

Question

I'm very new to C++, but I've been digging around and the general answer is no, c++11 does not support variable sized arrays, since array sizes need to be constant expressions.

However, I've tried this code on XCode 11 (C++11):

#include <iostream>

using namespace std;

int main(int argc, const char * argv[]) {

    unsigned long arrayS;
    cin >> arrayS;

    bool a[arrayS];

    return 0;
}

and it totally works. When I set a breakpoint at

bool a[arrayS];

I can see that the array a has arrayS elements. I have verified this with

*(&a + 1) - a

and it shows that the number of elements in a is arrayS.

Does c++11 support variable sized arrays? Or, is it only working for me because of the compiler I'm using?

I'm asking this question because I'm unsure of what compiler my friend is using and want to send the code to him to run.

Any help is much appreciated.

Answer 1

That is non standard C++. Some compilers accept it, but if you want to be portable you should stick with standard C++.