Preg match for all phone numbers starting with 07045

Question

I'm trying to add some code that prevents a form entry if the phone number starts with 07405. I've tried the following with no such luck, any ideas?

HTML field:

        <input type="tel" name="required[phone]" placeholder="Telephone Number" data-required="strict">

PHP:

  case 'phone';

           $phone = (sanitize_text_field($fields['phone']));
          if (preg_match('07045', $phone))
          {

            $fields['valid_phone'] = $phone;
            unset($fields['phone']);
          }
          else
          {
            unset($fields['phone']);
            array_push($errors, 'phone');
          }
          break;

Cheers, Dan

Answer 1

You forgot delimiters at preg_match, and beginning of string (you try to match substring in whole string).

preg_match('~^07045~', $phone)

The second thing is that regex isn't necessary for this task, substr will be faster.

if (substr($phone, 0, 5) == '07045')

Answer 2

use

preg_match('/^07045/',$phone);

Answer 3

You can also use strpos() for this, to avoid regex:

if ( strpos( $phone, '07045' ) === 0 ) 

Answer 4

You should do this check at client side using javascript or jQuery.
For php use, preg_match('/^07405/',(string)$phone)