Before main()

Understanding OS program initialization and the before-main sequence

This is an easy multiple-choice question that tests knowledge of what happens before a program's main() function executes. It's the kind of foundational question interviewers ask to confirm you understand how an operating system actually loads and prepares a process for execution.

To answer it well, you need to be familiar with the typical sequence of OS-level setup: memory allocation, loader behaviour, stack and heap initialization, and any runtime setup code that runs before user code begins. The question asks you to identify which operation is not part of this sequence—so understanding the full picture of what the OS does do is essential.

• Process creation and address space setup
• Loader responsibilities and executable format handling
• Runtime initialization vs. OS kernel responsibilities
• Memory layout: text, data, heap, and stack segments