<?php $data = range(1, 18); // You can either index by 0 and add one, or 1 and subtract one for($i = 1; $i <= count($data); $i++) { // Variable for easier reference later $item = $data[$i - 1]; // On the fifth item, emit logic for just one if(0 === $i % 5){ echo 'Single: ' . $item; }else { // Grab the next if it exsts $next = $data[$i++] ?? null; if($next){ echo 'Double: ' . $item . ', ' . $next; }else{ echo 'Double: ' . $item; } } echo PHP_EOL; }
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