C++ Coding Standards: 101 Rules, Guidelines, and Best Practices

96. Don’t memcpy or memcmp non-PODs

Summary

Don’t try to X-ray objects (see Item 91): Don’t use memcpy and memcmp to copy or compare anything more structured than raw memory.

Discussion

memcpy and memcmp violate the type system. Using memcpy to copy objects is like making money using a photocopier. Using memcmp to compare objects is like comparing leopards by counting their spots. The tools and methods might appear to do the job, but they are too coarse to do it acceptably.

C++ objects are all about information hiding (arguably the most profitable principle in software engineering; see Item 11): Objects hide data (see Item 41) and devise precise abstractions for copying that data through constructors and assignment operators (see Items 52 ...