How to get first 5 characters from string using php

The following PHP snippet will get the first 5, 10, 20, or 50 characters from a variable.

example:
$myStr = "HelloWordl";
Result like this
$result = "Hello";

Here's the ticket!
singlebyte strings
substr($myStr, 0, 5);

multibyte strings
mb_substr($myStr, 0, 5);