How can regular expressions be used to extract values from a string in PHP?

Regular expressions can be used in PHP to extract specific values from a string by defining a pattern that matches the desired content. This pattern can include specific characters, words, or sequences that need to be extracted. By using functions like preg_match() or preg_match_all(), you can apply the regular expression pattern to the string and retrieve the matching values.

$string = "Hello, my phone number is 123-456-7890";
$pattern = "/\d{3}-\d{3}-\d{4}/"; // Regular expression pattern to match phone number format

if (preg_match($pattern, $string, $matches)) {
    $phone_number = $matches[0];
    echo "Phone number extracted: " . $phone_number;
} else {
    echo "Phone number not found in the string.";
}