Regex in PHP

$str = "Jane\tKate\nLucy Marion";
$regex = "@\s@";
// Output: Array("Jane", "Kate", "Lucy", "Marion")
print\_r(preg\_split($regex, $str));

$arr = ["Jane", "jane", "Joan", "JANE"];
$regex = "/Jane/";
// Output: Jane
echo preg\_grep($regex, $arr);

$regex = "/[a-zA-Z]+ (\d+)/";
$input\_str = "June 24, August 13, and December 30";
if (preg\_match\_all($regex, $input\_str, $matches\_out)) {
    // Output: 2
    echo count($matches\_out);
    // Output: 3
    echo count($matches\_out[0]);
    // Output: Array("June 24", "August 13", "December 30")
    print\_r($matches\_out[0]);
    // Output: Array("24", "13", "30")
    print\_r($matches\_out[1]);
}

$str = "Visit QuickRef";
$regex = "#quickref#i";
// Output: 1
echo preg\_match($regex, $str);

$str = "Visit Microsoft!";
$regex = "/microsoft/i";
// Output: Visit QuickRef!
echo preg\_replace($regex, "QuickRef", $str);