<?php
 
$array = array(11,12,15,16,17,18,22,23,24);
$break_start = array();
 
//range finder
for ($i=0; $i<sizeof($array); $i++) {
	$current = $array[$i]; 
	$previous = $array[$i-1];
	if ($current==($previous+1)) { 
		//no break points are found 
	} else { 
		//return break points with keys intact
	    array_push($break_start, $i);
	}
 
}
 
for ($i=0; $i<sizeof($break_start); $i++) {
	$key = $break_start[$i];
	$next_key = $break_start[$i+1];
 
	//if last iteration
	if ($i==sizeof($break_start)-1) { 
		echo "Range: ".$array[$key]." - ".$array[count($array)-1]." \n"; 
		} 
	else { 
		echo "Range: ".$array[$key]." - ".$array[$next_key-1]." \n";	
		}
}

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