Online PHP editor | refs for TBbUF

<?php $j[] = 'ma_1_49812_5318.jpg'; $j[] = 'ma_1_49812_5319.jpg'; $j[] = 'ma_1_49813_5320.jpg'; $j[] = 'ma_1_49813_5321.jpg'; $result = []; foreach ($j as $filename) { $groupBy = preg_replace('/_[^_]+$/', '', $filename); if (!isset($ref[$groupBy])) { $ref[$groupBy] = $filename; $result[] = &$ref[$groupBy]; } else { $ref[$groupBy] .= "|$filename"; } } var_export($result);