Какая функция нужна для разбиения строки на части php?

explode(string $separator, string $string, int $limit = PHP_INT_MAX): array

<?php

$pie  = "piece1 piece2 piece3 piece4 piece5 piece6";
$pieces = explode(" ", $pie);
print_r($pieces); // => ["piece1", "piece2", "piece3", "piece4", "piece5", "piece6"]

str_split(string $string, int $length = 1): array

<?php

$str = "Hexlet";

$arr1 = str_split($str);
$arr2 = str_split($str, 3);

print_r($arr1); // => ["H", "e", "x", "l", "e", "t"]
print_r($arr2); // => ["Hex", "let"]