perl split whitespace

sharky · 10-22-2008, 06:58 PM

If I split a string that has lots of white space between strings I get some fields in the resulting array that are spaces.

For example:

Code:

#!/usr/bin/perl

$S1 = " a b c   d   e f";
@A1 = split (/ /,$S1);
print "$A1[0]\n";
print "$A1[1]\n";
print "$A1[2]\n";
print "$A1[3]\n";
print "$A1[4]\n";
print "$A1[5]\n";

this returns the following:

a
b
c

d

I can edit the file to merge the whitespace but I'm wondering if there's a way to do this with split. I would also like the leading space to be ignored.

gilead · 10-22-2008, 07:50 PM

I'm not at a box where I can test it, but does the following work? The + means one or more spaces:

Code:

#!/usr/bin/perl

$S1 = " a b c   d   e f";
@A1 = split (/ +/,$S1);
print "$A1[0]\n";
print "$A1[1]\n";
print "$A1[2]\n";
print "$A1[3]\n";
print "$A1[4]\n";
print "$A1[5]\n";

sharky · 10-22-2008, 08:30 PM

Quote:

Originally Posted by gilead

I'm not at a box where I can test it, but does the following work? The + means one or more spaces:

Code:

#!/usr/bin/perl

$S1 = " a b c   d   e f";
@A1 = split (/ +/,$S1);
print "$A1[0]\n";
print "$A1[1]\n";
print "$A1[2]\n";
print "$A1[3]\n";
print "$A1[4]\n";
print "$A1[5]\n";

Cool, that did it.

I added this to get rid of the leading white space.

$S1 =~ s/^\s+//;

Thanks for the help.

gilead · 10-22-2008, 09:22 PM

No problem - I'm glad it's working

Telemachos · 10-23-2008, 07:13 AM

It's a small thing, but I prefer to use \s+ rather than / +/ always, because it helps me to see more quickly that I am looking for whitespace. Also /\s+/ and / +/ don't match exactly the same way.

Code:

#!/usr/bin/perl
use strict;
use warnings;

my $string = "a  b\tc    d     e  f ";
my @array1 = split /\s+/, $string;
my @array2 = split / +/, $string;

print "\nSplit on \\s+\n";
foreach my $item (@array1) {
  print "$item spaces?\n";
}

print "Split on / +/\n";
foreach my $item (@array2) {
  print "$item spaces?\n";
}

Output:

Code:

telemachus ~ $ ./test 
Split on \s+
a spaces?
b spaces?
c spaces?
d spaces?
e spaces?
f spaces?

Split on / +/
a spaces?
b       c spaces?
d spaces?
e spaces?
f spaces?

sharky · 10-23-2008, 10:47 AM

Telemachos, thanks for the tip.