Cache-Friendly

What this C++ cache-locality question tests

This is a medium-difficulty C++ question that probes your understanding of how memory layout and access patterns affect runtime behaviour. Rather than asking you to write code from scratch, it presents a concrete snippet and asks you to predict its output — a format that rewards deep knowledge of language semantics and hardware-conscious programming.

To answer correctly, you need to reason carefully about how C++ lays out data structures in memory, how the compiler optimises access patterns, and how those patterns influence what gets computed and printed. These questions are common at firms where engineers need to write cache-friendly code, because predicting behaviour requires you to think like both the compiler and the CPU.

• Memory layout and alignment of compound types
• Loop unrolling and vectorisation
• Cache line boundaries and temporal locality
• Order of evaluation and undefined behaviour in C++