If substr's okay, how about this kind of thing:

my $string = "This is a very long string";
foreach (0..length($string))
{
        if(substr($string, $_, 1) eq " ")
        {
                    # Replace this position (space) with a "|"
                substr($string, $_, 1, "|");
        }
}
print $string;
[download]

It kinda depends on what you're trying to do, but I think this might help. (Note that you can also replace with the empty string).

Hope it does.

jarich

Update: forgot the length. ;)