memset() on objects.

Understanding memset() behaviour on C++ objects

This is an easy C++ language-knowledge question that tests whether you understand the difference between low-level memory operations and object semantics. It's the kind of trap question quant trading firms use to identify candidates who can write safe, predictable code in performance-critical systems.

The question probes a common misconception: that memset(), which operates on raw bytes, is safe to use on arbitrary C++ objects. In reality, blanking memory with memset() bypasses constructors, destructors, and the object model itself—leading to undefined behaviour, memory corruption, or resource leaks depending on what the object contains. This matters especially in trading systems, where correctness and determinism are non-negotiable.

• When memset() is safe (POD types and trivial layouts)
• How constructors and destructors interact with raw memory operations
• Safe alternatives: value initialization, std::fill(), and explicit member zeroing