How to validate phone numbers?

Question

MySQL

Hello.
There is a list of phone numbers of users from VK.
As you know, 80% of users write anything in this field, but not a phone number, and the remaining 20% ​​write it in different formats. How can I select real numbers?
Numbers are only Russian, start with 7, +7, 8 or no prefix at all...
The number itself is 9 characters with a code. There can be any characters between characters (brackets, hyphens, spaces)

Answer 1

You need to cut off spaces, pros and cons. Then compare the length of the number and check that it consists only of digits. You can do something like this:

$phonenumber = '...';
$phonenumber = preg_replace('/(\-|\s|\+)/i', '', trim($phonenumber));
if (strlen($phonenumber) == 9 && preg_match('/^\d+$/i', $phonenumber)) {
    echo 'valid';
} else {
    echo 'invalid';
}

Of course, valid will only be if the person indicated the full number with the code.

Answer 2

Here is another lib for validating phone numbers (php)
pakagist