Stdmemmove

Stdmemmove is a function in the standard memory manipulation library used by several programming environments to move a sequence of bytes from a source region to a destination region, allowing the source and destination to overlap. It is functionally equivalent to memmove in C, and is designed to be safer than memcpy for overlapping regions.

Prototype: void *stdmemmove(void *dest, const void *src, size_t n); It returns a pointer to dest. The operation copies n bytes from src to dest and does not modify data beyond those bytes.

Behavior with overlap: When the source and destination buffers overlap, stdmemmove ensures the bytes are copied in a way that the resulting block reflects the source data prior to the call. The exact copying order is implementation-defined; some implementations copy forward when dest < src and backward when dest > src.

Performance and implementation: The function may be implemented using temporary buffering or by directional copying; performance varies by platform and compiler. In practice, stdmemmove is designed to be as efficient as memmove across hardware.

Safety and usage: Pointers must be valid for reading or writing n bytes; if not, the behavior is undefined. It is not safe to rely on overlap semantics with volatile memory or memory-mapped I/O. Use stdmemmove whenever overlap is possible to ensure correct results.

See also: memmove, memcpy, memory manipulation functions.