Why is Perl inconsistent with sprintf rounding?

Question

Here is a Perl script:

#!/usr/bin/perl

use strict;
use warnings;
use feature \'say\';

my @numbers = qw(
    0.254
    0.255
    0.256
);

foreach my $number (@         


        

Answer 1

If you add this line:

$number = sprintf '%.15f', $number;

before printing, you will have:

0.254000000000000 => 0.25
0.255000000000000 => 0.26
0.256000000000000 => 0.26
100.254000000000005 => 100.25
100.254999999999995 => 100.25
100.256000000000000 => 100.26

as you can see, 100.255 is not exactly 100.255 this is due to representation of float numbers.