Question

I know free() won’t call the destructor, but what else will this cause besides that the member variable won’t be destructed properly?

Also, what if we delete a pointer that is allocated by malloc?

Answer 1

It is implementation defined whether new uses malloc under the hood. Mixing new with free and malloc with delete could cause a catastrophic failure at runtime if the code was ported to a new machine, a new compiler, or even a new version of the same compiler.