Interestingly, the "use integer" line did absolutely nothing for me on 32-bit Windows XP TinyPerl 5.8. I tried to run it on Linux with 64-bit Perl 5.36, and to my surprise, it didn't even run! :-O It produced no error message and no output at all. The program does have a for loop in it, but it looked like it didn't even start the loop. I don't understand... Here's the program again:

#!/usr/bin/perl

use strict;
use warnings;
use integer;

$| = 1;

my $MAXQUAD = 18446744073709551615;

for (my $i = 9007199254740000; $i <= $MAXQUAD; $i++)
{
  printf("\n %.0f   %d", $i, $i);
}
[download]

So, anyway, I did notice that if I remove the "use integer" line, then the program runs. In fact, if I started the loop at, let's say, 4611686018420000000, then it will keep counting on the 64-bit Perl in Linux. Interesting!

However, when I stop the program by pressing CTRL+C, I notice something else. When printing the number $i as float, it sort of loses precision, but when printing it as %d number, it prints it precisely. In TinyPerl, I had the opposite experience with this where %f printed more precise values than %d. This is so weird... :P

 4611686018420022272  4611686018420022338
 4611686018420022272  4611686018420022339
 4611686018420022272  4611686018420022340
 4611686018420022272  4611686018420022341
 4611686018420022272  4611686018420022342
 4611686018420022272  4611686018420022343
 4611686018420022272  4611686018420022344
 4611686018420022272  4611686018420022345
 4611686018420022272  4611686018420022346
 4611686018420022272  4611686018420022347
 4611686018420022272  4611686018420022348
 4611686018420022272  4611686018420022349
 4611686018420022272  4611686018420022350
[download]