What are the advantages of using mb_* functions for handling UTF-8 strings in PHP?

When working with UTF-8 strings in PHP, it's important to use the mb_* functions for proper handling of multibyte characters. These functions are specifically designed to work with multibyte character encodings like UTF-8, ensuring that string manipulation operations such as length calculation, substring extraction, and case conversions are done correctly.

// Example code snippet demonstrating the use of mb_* functions for UTF-8 string manipulation
$utf8String = "こんにちは"; // UTF-8 string
$length = mb_strlen($utf8String); // Get the correct length of the string
$substring = mb_substr($utf8String, 0, 3); // Get a substring of the string
$upperCase = mb_strtoupper($utf8String); // Convert the string to uppercase
echo $length . "\n"; // Output: 5
echo $substring . "\n"; // Output: こんに
echo $upperCase . "\n"; // Output: こんにちは