Re: memset (0, 0, 0);

Andreas Schwab
2003-04-04T15:21:41Z

Joern Rennecke <joern.rennecke@superh.com> writes:

|> So, as i understand this, this means that the first argument of memset
|> must point to an object, which contains at least one (the first)
|> character. Passing a NULL pointer, or any other address which is
|> outside the address space of the program, invokes undefined behaviour.

IMHO 7.21.1[#2] gives the definitive answer:

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.

7.21.6.1 (The memset function) does not say otherwise.

Andreas.

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