For question 1, whatever happened to coding things the old-fashioned way?

# to split a string $string into substrings of size $len ... 

for($i=0;$i < length($string)/$len; $i++) {
    $codons[$i] = substr($string,$i*$len,$len);
}

[download]
For question 2, why not something like this? No ugly regexp tricks, no ugly grep syntax, just the straighforward brute force encoding of the algorithm. Why is there an obsession with obscure one liners here, anyway? 

$start=0;
for ($pos=0; $pos < length($string)-1;$pos++) {
    if ( substr($string,$pos,1) ne 
         substr($string,$pos+1,1) ) {
        $runs[$i++] = substr($string, $start,$pos-$start+1);
        $start=pos;
     } # end check for end of run
} # end loop across letters of string

$runs[$i++] = substr($string,$start,$pos-$start+1);

[download]

In reply to Re: Puzzlement in Splitsville by Anonymous Monk
in thread Puzzlement in Splitsville by tlm

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