Subject: Hint on sp1

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The value returned by sscanf() with %d format codes can
be viewed separate cases:

-1 => there was nothing but whitespace characters between
      the start of buffer pointer and the NULL at the end
      of the string

 0 => there was some non-whitespace but the first field
      encountered was not a decimal number

>0 => one or more numeric fields was successfully obtained.

Therefore, if your .ppm header looks like
P6
1024 768
255

and you use
count = sscanf(buf + 2, "....")
you will set count to -1 which is a BAD THING!!!!!!!!!!

Thus it is advisable to do something along the lines
of

   status = sscanf(...);
   if (status > 0)
      count += status;