Program termination via std::exit or std::abort: what happens to destructors of automatic (stack) objects in C++?

Introduction / Context:Automatic objects normally have their destructors run when their scope ends. However, abnormal or immediate termination paths behave differently. This question targets the behavior of std::exit and std::abort with respect to stack unwinding.

Given Data / Assumptions:

• Automatic storage duration objects reside on the stack.
• std::exit performs normal termination without unwinding stack frames.
• std::abort terminates the process immediately.

Concept / Approach:When std::exit is called, stack unwinding does not occur, so destructors for automatic (block-scope) objects are not called. Registered atexit handlers run, and static-duration objects may be destroyed. std::abort is harsher: it terminates immediately and does not call destructors or atexit handlers. Therefore, for automatic objects, the correct answer is that destructors are not called.

Step-by-Step Solution:1) Local object inside a function → normally destroyed at scope end.2) Call std::exit(n) inside the function → the function never returns; no stack unwinding → no local destructor calls.3) Call std::abort() → immediate termination; no destructors of any kind are run.4) Therefore: “are not called”.

Verification / Alternative check:Insert logging in destructors; compare a normal return path vs. calling std::exit or std::abort to observe the difference.

Why Other Options Are Wrong:are called/are created/are inherited: contradict termination semantics.Special-casing main(): termination behavior is not limited to main's locals; the rule concerns stack unwinding globally.

Common Pitfalls:Relying on stack object destructors for critical cleanup during process termination; prefer RAII plus ensuring normal shutdown paths, or register handlers as appropriate.

Final Answer:are not called