Do I need to treat cases when I actully have nothing to move/copy with memmove()
/memcpy()
as edge cases
int numberOfBytes = ...
if( numberOfBytes != 0 ) {
memmove( dest, source, numberOfBytes );
}
or should I just call the function without checking
int numberOfBytes = ...
memmove( dest, source, numberOfBytes );
Is the check in the former snippet necessary?
From the C99 standard (7.21.1/2):
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.
So the answer is no; the check is not necessary (or yes; you can pass zero).