Removing leading zeros

idunno has asked for the wisdom of the Perl Monks concerning the following question:

Replies are listed 'Best First'.
Re: Removing leading zeros by suaveant (Parson) on May 15, 2001 at 00:36 UTC
Just use it as a number, like `$var + 100` or `$var == 6` as long as you do that, perl will treat it as a number and ignore leading zero's, if you do `$var eq 6` it will not remove zeros, because eq is for strings... to just convert it directly to a number for peace of mind you can do `$var += 0` which will turn 00005.67 into 5.67 in $var. - Ant	[reply] [d/l] [select]
Re: Removing leading zeros by FouRPlaY (Monk) on May 15, 2001 at 00:34 UTC
I'd do it with a regex like: `s/^0+//g` FouRPlaY Learning Perl or Going To die() Trying	[reply] [d/l]
Re^2: Removing leading zeros by Anonymous Monk on Apr 22, 2019 at 15:07 UTC
That RE fails multiple edge cases. It will change "0", or "00", etc. into "" making it non-numeric. And not handling the negative case has already been mentioned.	[reply]
Re: Removing leading zeros by cLive ;-) (Prior) on May 15, 2001 at 03:38 UTC
Argh, everybody's gone regex mad! if you're using the number mathematically, you don't need to remove the leading zeroes; or $var+=0; cLive ;-)	[reply]
(Ovid) Re: Removing leading zeros by Ovid (Cardinal) on May 15, 2001 at 00:34 UTC
`perl -e '$_="000abc";s/^0*//;print'` [download] Cheers, Ovid Join the Perlmonks Setiathome Group or just click on the the link and check out our stats.	[reply] [d/l]
Benchmarking Removing leading zeros by grinder (Bishop) on May 15, 2001 at 12:48 UTC
Looks like += 0 is the winner, sprintf is the loser and regex comes somewhere in the middle. `#! /usr/bin/perl -w use strict; use Benchmark; my $start = shift; timethese shift, { Add => sub { my $num = $start; $num += 0 }, Regex => sub { my $num = $start; $num =~ s/^0+// }, Sprintf => sub { my $num = $start; $num = sprintf '%d', $num }, };` [download] % perl zero 0000000000000000000000123 2000000 Benchmark: timing 2000000 iterations of Add, Regex, Sprintf... Add: 10 wallclock secs ( 9.30 usr + 0.00 sys = 9.30 CPU) Regex: 10 wallclock secs (10.30 usr + 0.00 sys = 10.30 CPU) Sprintf: 15 wallclock secs (14.39 usr + 0.02 sys = 14.41 CPU) % perl zero 0123 2000000 Benchmark: timing 2000000 iterations of Add, Regex, Sprintf... Add: 8 wallclock secs ( 8.77 usr + 0.00 sys = 8.77 CPU) Regex: 11 wallclock secs ( 9.88 usr + 0.00 sys = 9.88 CPU) Sprintf: 13 wallclock secs (11.95 usr + 0.00 sys = 11.95 CPU) -- `g r i n d e r`	[reply] [d/l]
Re: Removing leading zeros by wardk (Deacon) on May 15, 2001 at 02:31 UTC
didn't see a sprintf solution... `#!/usr/bin/perl use strict; my @num = ( "000006", "00005.55", "0004.5650"); foreach (@num) { print $_, " becomes: "; print sprintf("%d\n", $_); }` [download] which produces.... `000006 becomes: 6 00005.55 becomes: 5 0004.5650 becomes: 4` [download]	[reply] [d/l] [select]
Re: Removing leading zeros by Banky (Acolyte) on May 15, 2001 at 00:37 UTC
If you need to worry about possible negatives. `$num=~s/^(-?)0*/$1/;` [download]	[reply] [d/l]
Re: Removing leading zeros by physi (Friar) on May 15, 2001 at 00:53 UTC
Sorry brother's, but the following doesn't work like idunno needs it: `perl -e ' $e = 0034; $e+=0;print $e'` [download] Gives us 28 instead of 34 !!! This only work if we change this to: `perl -e ' $e = "0034"; $e+=0;print $e'` [download] What happens is that the number 0034 is internaly used by perl as an octal number. And octal 034 is Dec: 28 !!! what can we do ??? Any hints ? `----------------------------------- --the good, the bad and the physi-- -----------------------------------` [download]	[reply] [d/l] [select]
Re: Re: Removing leading zeros by chipmunk (Parson) on May 15, 2001 at 01:07 UTC
Octal interpretation only happens for constants. Removing leading zeroes from a constant is trivial; you just use the Delete key on your keyboard. Removing leading zeroes from a number held in a variable (presumably what the original poster was asking) is a different question; various solutions have already been provided. In this case, however, suaveant is correct that you don't need to remove the leading zeroes. If you treat the value as a number, Perl is happy to oblige!	[reply]