Decades with years by range of Years (PHP)

decades_function.php

/* To get a list of decades with the years, from a range selection. Useful for navigational elements on webpages, for example. */

Array
(
    [2010] => Array
        (
            [0] => 2018
            [1] => 2017
            [2] => 2016
            [3] => 2015
            [4] => 2014
            [5] => 2013
            [6] => 2012
            [7] => 2011
            [8] => 2010
        )

    [2000] => Array
        (
            [0] => 2009
            [1] => 2008
            [2] => 2007
            [3] => 2006
            [4] => 2005
            [5] => 2004
            [6] => 2003
            [7] => 2002
            [8] => 2001
            [9] => 2000
        )

  ....

)

*/

$decades = decades_from_year(1972, 2018);

function decades_from_year($start_year, $end_year) {
	$decades = array();
	foreach(range($end_year, $start_year) as $year) {
		$decades[substr(($year), 0, -1)."0"][] = $year;
	}
	return $decades;
}