[LLVMdev] memcpy(), memmove(), and memset() with zero length

[Dale Johannesen]

On Oct 6, 2007, at 9:02 AM, Jon Sargeant wrote:

> If I copy or set zero bytes with memcpy(), memmove(), or memset(), can
> the <dest> and <src> arguments be null?  Can they be invalid pointers?

This is covered in 7.21.1.p2 of C99 (C++ just points to the C standard):

Where an argument declared as size_t n specifies the length of the  
array for a
function, n can have the value zero on a call to that function.  
Unless explicitly stated
otherwise in the description of a particular function in this  
subclause, pointer arguments
on such a call shall still have valid values, as described in 7.1.4.  
On such a call, a
function that locates a character finds no occurrence, a function  
that compares two
character sequences returns zero, and a function that copies  
characters copies zero
characters.