How can the word class \w be used in regex patterns in PHP?

The word class \w in regex patterns matches any word character, which includes letters, digits, and underscores. To use it in PHP regex patterns, simply include \w in your regex pattern where you want to match word characters. This can be useful when you need to find or validate words in a string.

$string = "Hello123_world";
if (preg_match('/\w+/', $string)) {
    echo "String contains word characters.";
} else {
    echo "String does not contain word characters.";
}