What are the differences between ICONV_ and MB_ functions in PHP when dealing with UTF-8 encoding?

When dealing with UTF-8 encoding in PHP, the ICONV_ functions are typically used for converting between different character encodings, while the MB_ functions are used for handling multi-byte character strings. ICONV functions are more focused on character encoding conversion, while MB functions provide more functionality for working with multi-byte strings in various encodings.

// Example of using ICONV functions for encoding conversion
$utf8_string = "Hello, 你好";
$converted_string = iconv("UTF-8", "ISO-8859-1", $utf8_string);
echo $converted_string;

// Example of using MB functions for multi-byte string manipulation
$utf8_string = "Hello, 你好";
$length = mb_strlen($utf8_string, "UTF-8");
echo "Length of string: " . $length;