Padded Layout

What this C++ memory-layout interview question tests

This is a hard question that probes deep knowledge of how C++ allocates and pads data structures in memory. It's the kind of question used to distinguish candidates who understand the compiler's decisions from those who only know syntax.

To answer it correctly, you need to reason about struct layout rules: alignment requirements of individual members, padding insertion between fields, and how the compiler arranges everything to satisfy alignment constraints. The question rewards candidates who can mentally execute the layout algorithm and predict the exact bytes the compiler will generate—not just guess.

• Alignment and padding in structs
• Size of fundamental types across platforms
• Compiler layout algorithms and their tradeoffs
• How sizeof relates to member order