Re: Dividing and format with regular expression the perl way

Yes, you can certainly do this without using printf or sprintf. Number can be treated as string in perl. I will provide a simple regular expression solution since nobody has thought about it yet. ;-)

#!/usr/local/bin/perl -w
use strict;

my $xx = 12000/1000;   # wanted result is 12.0
my $yy = 12678/1000;   # wanted result is 12.7 - rounded up

print "\$xx = ", rounding_with_regex($xx), "\n";
print "\$yy = ", rounding_with_regex($yy), "\n";

sub rounding_with_regex
{
  my $num = shift;
  $num += 0.05;            # want to round up (as number)
  $num =~ s/\.(\d).*/.$1/; # perform the rounding (as string)
  return $num;
}
[download]

And the output is exactly as required -

$xx = 12.0
$yy = 12.7
[download]

Comment on Re: Dividing and format with regular expression the perl way Select or Download Code

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Re: Re: Dividing and format with regular expression the perl way by Anonymous Monk on Nov 27, 2003 at 20:35 UTC
`$num =~ s/\.(\d).*/.$1/; # perform the rounding (as string)` [download] Oi Vay! Why (oh why) do you have that trailing dot-star in your regex? I see this with both neophyte and experienced RE users and I have yet figure out what misconception leads to this practice. Any ideas?	[reply] [d/l]
Re: Re: Re: Dividing and format with regular expression the perl way by Roger (Parson) on Nov 27, 2003 at 20:42 UTC
Well, just drop trailing dot-star in the regex and see the result. ;-) I want to get rid of anything after the first decimal point, the tailing (.) let me do that. Of course I can also rewrite the regular expression as - `$num =~ s/\.(\d)\d+/.$1/; # perform the rounding (as string)` [download] But that requires 3 characters, and I am just too lazy*. Besides there is an assumption that whatever passed in is a floating point.	[reply] [d/l]
Re: Re: Re: Dividing and format with regular expression the perl way by ysth (Canon) on Nov 27, 2003 at 20:39 UTC
In this case, it removes anything after the first decimal. Perhaps you are thinking of needless .* at the end of a m//?	[reply]


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