One of these mains.

Understanding valid main function signatures in C++

This is an easy practice question that tests knowledge of the C++ standard and what constitutes a valid program entry point. It asks you to distinguish between compliant and non-compliant declarations of the main function by reading a code snippet and identifying which signature violates the language specification.

Interviewers—especially at firms that hire systems engineers or high-frequency trading developers—use questions like this to confirm that candidates understand the formal rules governing the most fundamental function in any C++ program. The standard is strict about what forms main may take, and correct answers require familiarity with both the two-argument and zero-argument forms, return types, and constraints on storage class.

• Standard-compliant main signatures
• Return types and argument counts
• Implicit vs. explicit entry-point declarations