php get only numbers from string

phpCopy<?php 
$string = 'Sarah has 4 dolls and 6 bunnies.';
$outputString = preg_replace('/[^0-9]/', '', $string);  
echo("The extracted numbers are: $outputString \n"); 
?> 

function get_numerics ($str) {
    preg_match_all('/\d+/', $str, $matches);
    return $matches[0];
}

// this function will return an array of number

$str = "3 dogs were running!";
echo (get_numerics($str)[0]); 

// output 3

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

phpCopy<?php 
$string = 'Sarah has 4 dolls and 6 bunnies.';
preg_match_all('!\d+!', $string, $matches);
print_r($matches); 
?>