From: Daniel Koepke (dkoepke@CALIFORNIA.COM)
Date: 09/10/97

On Wed, 10 Sep 1997, Rich Chiavaroli wrote:

-+Well, just from what I've learned (the hard way I might add) if you
-+add the 4th "%d" on the the last line of values, you have to make sure
-+that (only if you're using Oasis I guess) you write out all 0's to that
-+field first.

Err, go back and read the message (and especially the pseudo-code)
again.  sscanf() does not require you to meet the format exactly and
returns how many things it could match to the given format.  For
instance, try:

  int i, j, k, l;
  i = j = k = l = 0;
  printf("%d: %d, %d, %d, %d", sscanf("2 5 6", "%d %d %d %d", &i, &j, &k, &l),
         i, j, k, l);

This will print:

  3: 2 5 6 0

Note that we have passed "2 5 6", which does not have four arguments
as the format "requires".  This is because it doesn't really require
the string to match the format, it just matches the string to the
format as best as it can.  In CircleMUD we get the restriction because
it tests how many variables matched the format and reports an error
if it doesn't meet the format "requirement".  In other words, Circle
does something along the lines of:

  if (sscanf("2 5 6", "%d %d %d", &i, &j, &k) != 3)

My suggestion was adding a fourth optional argument by making the != 3
"< 3".  In other words, the error is only reported if sscanf() gets
less than 3 arguments.  Otherwise it accepts 3 or 4 arguments (it won't
get five, because that goes beyond the format).  So, my change was:

  if (sscanf("2 5 6", "%d %d %d %d", &i, &j, &k, &l) < 3)

See?  We can get up to four arguments, but if we only get 3, we don't
report a problem.  We just let l alone unless we have enough arguments
in the first string ("2 5 6").  An actual implemetation of this
would lie along the lines of:

  if ((count = sscanf(line, " %d %d %d %d ", t, t+1, t+2, t+3)) < 3) {
    report the error;

  obj.value[0] = t[0];
  obj.value[1] = t[1];
  obj.value[2] = t[2]; /* required variables */
  obj.value[3] = (count > 3 ? t[3] : 0); /* optional */

Understand? [or did I misunderstand what you were saying]

Daniel Koepke -:- -:-  [Shadowlord/Nether]

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