You don't need a regex, you need printf and the related sprintf:

printf '$%.2f', 5.5;   #prints $5.50
printf '$%.2f', 9;     #prints $9.00
printf '$%.2f', 19.95; # print $19.95
[download]

HTH

@nums = (5.5, 9, 19.95);
print sprintf("\$%.2f\n", $_) foreach @nums;
[download]

__________________________________________________

s mmgfbs nf, nfyojy m,tr yb-zya-zy,s zfzphz,print;
- thanks japhy :)

mexnix.perlmonk.org

my @values = ('5.5', '9', '19.95');
foreach my $value (@values) {
    my $dollars = int $value;
    my $cents = $value - $dollars;
    my $converted_value = sprintf "\$$dollars.%02d", int ($cents * 100
+ + .5);
    print "$converted_value\n";
}

----

$5.50
$9.00
$19.95
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Here's a little code:

sub dollars_cents
{
    my $value = shift;

    my $comma = qq(,);
    my $count;
    my $dot = qq(.);
    my $dollar_sign = qq(\$);
    my @new_value;
    my $new_value;
    my @rvrs_value;
    my @value;

    $value =~ s/\D//g;
    @value = split (//,$value);
    @rvrs_value = reverse @value;
    push(@new_value, $rvrs_value[0]);
    shift @rvrs_value;
    push(@new_value, $rvrs_value[0]);
    shift @rvrs_value;
    push(@new_value, $dot);

    $count = 0;
    while (@rvrs_value)
    {  if ($count eq 3)
        {    push(@new_value, $comma);
            $count = 0;
        }
        else
        {   push (@new_value, $rvrs_value[0]);
            shift @rvrs_value;
            $count++;
        }
    }
    push(@new_value, $dollar_sign);
    @new_value = reverse(@new_value);
    $new_value = join(//,@new_value);
    return($new_value);
}
[download]

Janitored by Arunbear - added code tags, as per Monastery guidelines

Not a problem. Just take the routine and put it into a subroutine or method:

    sub convert_to_dollar_format {
        my $value = shift;
        $value   += 0;
        # cheap error checking.  You'll want something more robust
        return $value =~ /[^\d.]/ ? 0 : sprintf( '$%.2f', $value );
    }
[download]

With that sub, you just call it as you need it and don't worry about using the return value until necessary. Of course, you'll want to customize the error checking to fit your actual needs. Note that sprintf will not print the output (that was a concern you stated), but will merely format it properly).

As for a regex solution, I wouldn't use one. Regexes are expensive in terms of performance and shouldn't be used if less expensive operations are available.

Also, the reason you may want to update the error checking is due to it returning zero for non-numeric data. This is similar to Perl's handling of scalars, but probably is going to be harder to debug. I included the "add zero" line so the routine would warn about a non-numeric argument you if you have warnings enabled.

Cheers,
Ovid

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As documented, sprintf returns a string you do not have to immediately print. You can just take the result of sprintf and store it in a variable.

higle,
using s?printf in this context is not a kludge at all! It's simply the most straightforward way to get the job done, we're functions meant for this purpose.

Without thinking too much about it, I'd guess that a substitution regexp would require the e modifier to get the formatting job done. So it would be more cumbersome, more computationally expensive, harder to debug, probably uglier too :-)

-- TMTOWTDI