how to separate integer from string in php

 phpCopy<?php 
$string = 'Sarah has 4_dolls  8_dolls and 6 bunnies.';
$int = (int) filter_var($string, FILTER_SANITIZE_NUMBER_INT);  
echo("The extracted numbers are: $int \n"); 
?> 

$s = "1,2,3,8,2";
$ints = array_map('intval', explode(',', $s ));
var_dump( $ints );