Validate for more than one format with preg_match

Question

I have a phone number field that is set up to validate using preg_match:

function ValidPhone($phone) {
    return preg_match('/^[0-9]{3}-[0-9]{3}-[0-9]{4}$/', trim($phone));
}

This ensures that phone numbers are entered in the xxx-xxx-xxxx format and that it's numeric.

I'm not very familiar with regexp; can anyone tell me how I'd expand this to allow more than one format? i.e. xxx xxx xxxx or xxx.xxx.xxxx or (xxx) xxx-xxxx

Thanks.

Answer 1

I think the easiest solution would be to just strip out everything that isn't numeric first:

function ValidatePhone($phone) {
    $phone = preg_replace('/\D+/', '', $phone);
    return strlen($phone) == 10;
}

Since you are validating the format, and not the content, this should do it:

function ValidatePhone($phone) {
    $patterns = array(
        '\d{3}([-\. ])\d{3}\g{-1}\d{4}',
        '\(\d{3}\) \d{3}-\d{4}'
        );

    $phone = trim($phone);

    foreach ($patterns as $pattern) {
        if (preg_match('/^' . $pattern . '$/', $phone))
            return true;
    }

    return false;                                                                                                                   
}