Question

Is a NULL pointer allowed as the string to store result in in a call to sscanf?

I don’t find anything about it in any documentation but it seems to be working fine. Same thing with scanf.

Example:

int main(int arc, char* argv[])
{
  char* s = NULL;
  sscanf("Privjet mir!", "%s", s);
  printf("s: %s\n", s);
  return 0;
}

Output: s: (null)

Answer 1

No:

Matches a sequence of non-white-space
characters; the next pointer must be a
pointer to character array that is
long enough to hold the input sequence
and the terminating null character
(‘\0’), which is added automatically.
The input string stops at white space
or at the maximum field width,
whichever occurs first.

(http://linux.die.net/man/3/sscanf)