Question

I hate decimal numbers. For 1.005 I don’t get the result I expect with the following code.

#!/usr/bin/perl -w

use strict;
use POSIX qw(floor);

my $num = (1.005 * 100) + 0.5;
print $num . "\n";          # 101
print floor($num) . "\n";   # 100
print int($num) . "\n";     # 100

For 2.005 and 3.005 it works fine.

With this ugly “hack” I get the expected result.

#!/usr/bin/perl -w

use strict;
use POSIX qw(floor);

my $num = (1.005 * 100) + 0.5;
$num = "$num";
print $num . "\n";          # 101
print floor($num) . "\n";   # 101
print int($num) . "\n";     # 101

What is the correct way to do this?

Answer 1

floor() is not for rounding, it goes down to the nearest integer.

See this old post: How do you round a floating point number in Perl?