Removing spaces between single letters

Question

I have a string that may contain an arbitrary number of single-letters separated by spaces. I am looking for a regex (in Perl) that will remove spaces between all (unknown n

Answer 1

Your description doesn't really match your examples. It looks to me like you want to remove any space that is (1) preceded by a letter which is not itself preceded by a letter, and (2) followed by a letter which is not itself followed by a letter. Those conditions can be expressed precisely as nested lookarounds:

/(?<=(?

tested:

use strict;
use warnings;

use Test::Simple tests => 4;

sub clean {
  (my $x = shift) =~ s/(?<=(?

output:

1..4
ok 1
ok 2
ok 3
ok 4

I'm assuming you really meant one space character (U+0020); if you want to match any whitespace, you might want to replace the space with \s+.