- to construct an Acct at a pre-existing address, call placement-new, which implicitly uses Acct ctor
- to construct an Acct in stack or static memory (usually data segment), just call ctor explicitly
- to construct an Acct in heap, call new, which implicit uses ctor.
By the way, you can also allocate memory without calling ctor. The malloc() and q[ operator new ] can do that, as explained in [[moreEffC++]]