To sign or not to sign?

Understanding signed and unsigned integer behaviour in C++

This is an easy question that tests your grasp of a subtle but critical distinction in C++: how the language handles arithmetic and comparison involving signed and unsigned integers. It appears frequently in quant interviews because correctness at the bit level matters enormously in low-latency trading systems.

The question asks you to trace through a code snippet and predict its output. To answer it correctly, you need to understand what happens when signed and unsigned types interact in the same expression—specifically, the implicit type conversions that the compiler applies and how they affect the values you observe. This is a common source of bugs that can silently corrupt data or produce unexpected control flow.

• Type promotion rules in mixed arithmetic
• Sign extension vs. zero extension
• Comparison semantics across signedness boundaries