PHP Print_r()

<?php
print_r($array,boolean-return);
?>

<?php
$a = array('b' => 'bat', 'c' => 'cat', 'r' => 'rat');
echo print_r($a,true); 
echo "<hr>";
$b = array(bat,cat,rat);
echo print_r($b,true); 
echo "<hr>";
$c = array(bat,cat,rat);
foreach($c as $arr)
{
	echo $arr."<br>";
}
?>