Ok, here it goes, some points I noticed:

• You were not giving any parenthesis in your $find argument, so the $1 was not matching anything. I think this was the main thing that kept your attempt with eval from working.
• You were using double quotes for your "$1 " parameter, which was making it evaluate it at call time, so your subroutine never saw the $1, only a space.
• I tried enclosing the eval block in braces, but it does not work. I'm still a little bit puzzled about that.
• I'm sure the for loop can be done without the indexing, but I'm also sure you just did that as a quick hack, so I'm not going to try to correct it :-)

So the code below works:

print splitter($string,"<.*?>",'(\S{18})','$1 ');
sub splitter{
         my($string,$spliton,$find,$replace)=@_;
         my @array=split(/$spliton/,$string);
         my $i=0;
         my @splitters;
         my $str;
         while($string=~/($spliton)/g){
                 push @splitters,$1;
         }
         my $a;  
         for (@array){
         
                eval "s/$find/$replace/g; ";
                die "$@" if $@;
                $str.=$array[$i];
                $str.=$splitters[$i];
                $i++;
         }
         $str;
 }
[download]

I still think that eval'ing regular expressions in a quote block may be dangerous. But as long as you control the values of the expressions, it should be ok.

Hope this helps,

--ZZamboni