Castaway

Understanding C++ compilation errors and language rules

This is a medium-difficulty C++ question that tests your knowledge of language semantics and compiler behavior. Rather than ask you to write code, it presents a code snippet and requires you to identify which line will fail at compile time—a skill that separates candidates who understand the rules from those who rely on trial and error.

Questions like this reward deep familiarity with C++ type systems, scope rules, operator overloading, and the boundary between what the standard allows and what a compiler will reject. Interviewers use these to assess whether you can reason about code correctness without running it, a valuable trait in performance-critical environments where compilation speed and code review matter.

• Type conversions and implicit casting rules
• Const-correctness and reference semantics
• Operator precedence and function overload resolution
• Scope and linkage in the one-definition rule