Aha, I see, I thought it would work... I tried this:
if($str=~/[ATCG]+([ATCG])\.+$/)
{
   $last_char=$1;
   $rightmost_position_of_letter = rindex($str, $last_mapped_char);
}

[download]

and it seems to work. Does that make sense?

In reply to Re^2: Proper usage of rindex function? by Anonymous Monk
in thread Proper usage of rindex function? by Anonymous Monk

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