Question

I have a string of arbitrary length, and starting at position p0, I need to find the first occurrence of one of three 3-letter patterns.

Assume the string contain only letters. I need to find the count of triplets starting at position p0 and jumping forward in triplets until the first occurrence of either ‘aaa’ or ‘bbb’ or ‘ccc’.

Is this even possible using just a regex?

Answer 1

Moritz says this might be faster than a regex. Even if it’s a little slower, it’s easier to understand at 5 am. 🙂

             #0123456789.123456789.123456789.   my $string = "alsdhfaaasccclaaaagalkfgblkgbklfs";   my $pos    = 9;   my $length = 3;   my $regex  = qr/^(aaa|bbb|ccc)/;  while( $pos < length $string ) {       print "Checking $pos\n";            if( substr( $string, $pos, $length ) =~ /$regex/ ) {         print "Found $1 at $pos\n";         last;         }      $pos += $length;     }