\G Match only where previous m//g left off (works only with /g)

perl -e "$num = \"0000012345\"; $num =~ s/\G0/ /g;print $num"
[download]

Cheers,
Ovid

Update: Just saw merlyn's response and wanted to note that I have Effective Perl Programming. Where the heck do you think I got that regex? :)

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Just tried that with "0.5"" and didn't like the result. For a fix make the substitution the not quite so nice:

s/\G0(?=\d)/ /g;
[download]

Update
Fixed the RE for the common case of '0' as well...

$num =~ s/\G0/ /g;
[download]

Ahh yes. I remember creating that in response to a similar question a few years ago in comp.lang.perl.misc, and then Joseph copied it for his Effective Perl Programming book, and now it's become part of the culture. Not quite as impactful as the Schwartzian Transform, but I remember getting a few "ooohs" and "aaaahs" over the simplicity of that.

-- Randal L. Schwartz, Perl hacker

Please take the following with a grain of salt. Ovid has already given the best answer.
It makes me wince, now, but it was actually used in production to strip leading zeros from numbers in a list, in the first real Perl program I ever wrote.

#!/usr/bin/perl -w
@numberarray = qw(00000900011 10001000100 00022200101); 

for $digits (@numberarray){ 
    @temparray = split (//,$digits); 
    $incr=0; 

        while ($temparray[0] eq 0) {
           shift @temparray; $incr++;
        } 
        unshift (@temparray," "x$incr); 
        $digits = join('',@temparray);
        print "$digits\n";
}
[download]

I couldn't discover a better way than to shift out the zeroes and unshift the replacing text, then join the result together.
It isn't pretty, but, as far as I can tell, it doesn't break.

mkmcconn
novice

---

Update:
And now, a monk, I never would have posted this (wonderful what a few weeks at perlmonks can do), but if I had, I would have suggested to novice mkmcconn that even taken with a grain of salt, numerous difficulties in his solution could be avoided by writing it this way:

#!/usr/bin/perl -wl
use strict;
my @numberarray    = qw(000000 000002 001110 010201 010010 001000 0001
+20 010030); 

for (@numberarray){ 
    next if $_    == 0;
    my @array      = split //; 
    my $incr       = 0; 
    
    while ($array[0] eq 0) {
       shift @array;
       $incr++;
    } 
    unshift (@array,"\x20" x $incr); 
    print @array;
}
[download]

And then would have advised him (as a friend) of the topical difference between "Regex to zero suppress" and "Subroutine to remove zero-padding".

It will be interesting to find out what advice I might give myself someday, about this update.
mkmcconn

Something like this perhaps:

my @nums = qw(000001 000010 000100 001000 010000 100000);

foreach (@nums) {
  s/^(0+)/' ' x length $1/e;

  print "|$_|\n";
}
[download]

"Perl makes the fun jobs fun
and the boring jobs bearable" - me

$numString =~ tr/0/ /;
[download]

Only if you want "400.3" to become "4 .3".

-- Randal L. Schwartz, Perl hacker

Oh yes, good point old chap. I should learn not to post anything if the hour has "AM" in it.

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