Memcpy is IIRC one of two ways to do type-punning (reinterpretation of bytes as a different type) without undefined behavior in C, and the only one in C++. The

Memcpy is IIRC one of two ways to do type-punning (reinterpretation of bytes as a different type) without undefined behavior in C, and the only one in C++. The other one in C is using a union type (which results in undefined behavior in C++). The behavior is implementation-defined, for obvious reasons, but that's not the same as undefined.