I think it might be an out-of-date assertion, but I'm not sure either since I also hear it from people who seem to be well-versed in the C standard. The only pl

I think it might be an out-of-date assertion, but I'm not sure either since I also hear it from people who seem to be well-versed in the C standard. The only place in C17 where I can see memcpy singled out (6.5p6) also mentions copying "as an array of character type." The definition of memcpy itself just describes it as copying characters. It's true that some types can have bit patterns that are "trap representations," that is, they cause undefined behaviour when used, but memcpy can also create trap representations. You could memcpy to copy the bit pattern of a signalling NaN from an int into a float, for example. memmove on the other hand can't be implemented in standard C, but it can be implemented on most platforms using only implementation-defined behaviour, because casting a pointer to an intptr_t is implementation-defined, but on most platforms with a flat memory model, it gives you the linear memory address.