Hi ropey,

If I'm understanding your requirements correctly, you could use a negative-lookbehind assertion like this:

use strict;
use warnings;

my $string = '111111111:22222\:2222:333333333:4444444';

my @split  = split(/(?<!\\):/, $string);

print "Results:\n";
map { print "$_\n" } @split;
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Which produces this:

Results:
111111111
22222\:2222
333333333
4444444
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You'd still need to handle the escaped '\', but the above code at least doesn't split on ':' if it's preceded by '\'.  Of course, that doesn't take into account the situation where a backslash '\' is really the second of a pair of backslashes, as in:

my $string = 'AAA:BBB:CCC\\:CCC:DDD";
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... so it's really only a simplistic, partial solution.