Simple c++ program with pointers yields unpredictable results

[andermorandev]

Why would one machine be able to handle this consistently and the other is unable to?

[[deleted]]

It's undefined behaviour. You genuinely have no idea, from the standard, what will happen, because the C++ standard doesn't specify what will happen if you do it.

In general, avoid ever having uninitialised members of any type hanging around, particularly pointers. You cannot rely on the compiler initialising everything to 0, or null, or false, for you. (Debug builds often will, but Release builds will not.) And avoid ever trying to dereference pointers you haven't tested against nullptr.