In the context of PHP, what are the implications of using functions like utf8_decode when working with regex patterns and string validation?

When working with regex patterns and string validation in PHP, it is important to ensure that the encoding of the strings being processed is consistent. If you are dealing with UTF-8 encoded strings and using regex patterns, it is recommended to use functions like utf8_decode to convert the strings to a compatible format before applying the regex patterns. This ensures that the regex patterns work correctly with UTF-8 encoded strings.

// Example of using utf8_decode to convert UTF-8 encoded string before applying regex pattern
$inputString = "Café";
$decodedString = utf8_decode($inputString);

$pattern = '/^[A-Za-z\s]+$/'; // Example regex pattern to match only alphabetic characters and spaces

if (preg_match($pattern, $decodedString)) {
    echo "String is valid according to the regex pattern.";
} else {
    echo "String is not valid according to the regex pattern.";
}