structs of structs of structs

Understanding nested struct layouts in C++

This is an easy C++ language-knowledge question that tests your grasp of how the compiler organizes memory for nested aggregate types. It appears in screening rounds at quant firms, where solid fundamentals on data layout and struct semantics separate careful coders from those who guess.

To answer questions like this correctly, you need to reason about struct member ordering, padding, and alignment rules—the same principles that matter when optimizing hot-path data structures for low-latency trading systems. The question rewards tracing through the code mentally rather than relying on intuition, and it often exposes gaps in understanding of how C++ actually lays out objects in memory.

• Member alignment and padding within structs
• Nested aggregate initialization
• Compiler layout rules and how they affect sizeof()