Building the program below shows sprintf failing to zero
pad the generated string when built on linux. It zero pads
on all other unix platforms (and winnt). The following is
the Linux man page snippet for zero padding:

   "0      specifying zero padding.   For  all  conver-
           sions  except  n,  the  converted  value  is
           padded on the left with  zeros  rather  than
           blanks.   If  a  precision  is  given with a
           numeric conversion (d, i, o, u,  i,  x,  and
           X), the 0 flag is ignored."

#include <stdio.h>
#include <stdlib.h>

int
main(argc, argv)
int   argc;
char  *argv[];
{
   char buff[20];
   sprintf(buff, "%012s", "4D2"); /* ZERO pad */

   printf("buff: '%s'\n", buff);
   return 0;
}
If I compile and run this code on linux 6.0 I get:

buff: '         4D2'
If I compile it on any other platform i get:

buff: '0000000004D2'