You're volatile.

What this C++ volatile-keyword question tests

This is an easy conceptual question about the volatile qualifier in C++. It's designed to confirm that a candidate understands how the compiler treats volatile-qualified variables differently from ordinary ones, and why that distinction matters in systems programming and low-latency trading contexts.

The question asks you to predict the behavior of a code snippet. To answer correctly, you need to know that volatile tells the compiler that a variable's value may change outside the program's control (for example, via hardware registers, memory-mapped I/O, or concurrent threads), and therefore the compiler must not optimize away reads or writes to that variable. This is especially relevant in high-frequency trading, where code often interacts directly with hardware or synchronizes across threads without locks.

• Compiler optimizations and the as-if rule
• Memory ordering and visibility guarantees
• Common use cases: hardware registers, concurrent access, signal handlers