Non-const declaration of array

Question

I have been teaching myself programming for couple of years, and I was sure that if you need array declaration of a variable number you need to use malloc or

Answer 1

There is an extension of GCC mimicking C99 Variable Length Arrays. It's not standard C++.

However, even if you have this turned off, the posted code can compile. The standard does not require a diagnostic for this case: it's Undefined Behaviour, not an error.

In really obvious cases a compiler may choose to prevent you from writing this, but otherwise it is free to let you fail in peace.

Conclusion: don't be fooled by the compilation. It's still bad and wrong.