How Should My C Program Terminate Gracefully?

Understanding Program Termination in C

Premature program termination can lead to resource leaks and data corruption. C offers several mechanisms to end a program's execution, each with its own implications.

Recommended Approach: Return from Main

The most straightforward method is to return from the main function with a proper exit status. This ensures a clean termination and provides information to the caller about the program's execution. If an error condition requires termination, throw an exception and catch it in the main function before returning.

Caution: Throwing Exceptions

While throwing exceptions can trigger stack unwinding and cleanup, it's crucial to catch all exceptions because uncaught exceptions may not always perform unwinding. Therefore, catch exceptions in the main function and return an appropriate exit status.

Discouraged: Using std::exit

std::exit is discouraged as it does not perform stack unwinding and leaves objects on the stack undisposed. This can lead to resource leaks and undefined behavior.

Alternative Strategies

Other termination options exist, but they should be used judiciously:

• std::_Exit: Causes normal termination without calling atexit handlers.
• std::quick_exit: Performs normal termination and calls std::at_quick_exit handlers.
• std::exit: Calls std::atexit handlers and performs other cleanup before normal termination.
• std::abort: Used only for unexpected, severe errors. Causes an abrupt program termination without cleanup.
• std::terminate: Calls the std::terminate_handler, which by default invokes std::abort.

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