3v4l.org

run code in 300+ PHP versions simultaneously
<?php $array = array("100_1", "100_2", "100_3", "101_1", "102_1", "102_2", "103_1", "103_2", "103_3", "104_1", "104_2"); sort($array); foreach($array as $value) { $parts = explode('_', $value); $result[$parts[0]] = $value; } $result = array_values($result); print_r($result);

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32.92 ms | 402 KiB | 5 Q