Adding custom masks to phone numbers - php

Question

So i'm creating a simple function to mask phone numbers. My phone numbers have a 9 digits and i want preg_replace them with a given mask like 2-2-2-1-2 or 3-2-2-2 and etc.
I tried this:
$mask = explode('-', '3-2-2-2');
$pattern = '';
$replace = '';
foreach ($mask as $key => $value) {
if ($key == 0) {
$pattern = '/\(?(\d{' . $value . '})\)?[- ]';
$replace = '$' . ++$key . '-';
continue;
}
if ($key == count($mask) - 1) {
$pattern .= '?(\d{' . $value . '})/';
$replace .= '$' . ++$key;
break;
}
$pattern .= '?(\d{' . $value . '})[- ]';
$replace .= '$' . ++$key . '-';
}
return preg_replace($pattern, $replace, '902000810');
and the result is 902-00-08-10. Sometimes getting error preg_replace(): No ending delimiter '/' found. How can i refactor this to not getting errors?

Answer 1

Assuming:
$num = '902000810';
$mask = explode('-', '3-2-2-2');
There're other ways than using regex to format a phone number from the mask.
using formatted strings:
$maskPH = array_map(fn($i) => "%{$i}s", $mask);
$formatI = implode('', $maskPH);
$formatO = implode('-', $maskPH);
$result = vsprintf($formatO, sscanf($num, $formatI));
using unpack:
$format = array_reduce($mask, function ($c, $i) {
static $j = 0;
return "{$c}A{$i}_" . $j++ . "/";
});
$result = implode('-', unpack($format, $num));

Answer 2

preg_replace(): No ending delimiter '/' found
means that your pattern does not terminate with a / as last character.
But all three patterns lack proper formatting:
You should modify them accordingly.
From:
$pattern = '/\(?(\d{' . $value . '})\)?[- ]';
$pattern .= '?(\d{' . $value . '})/';
$pattern .= '?(\d{' . $value . '})[- ]';
To:
$pattern = '/\(?(\d{' . $value . '})\)?[- ]/';
$pattern .= '/?(\d{' . $value . '})/';
$pattern .= '/?(\d{' . $value . '})[- ]/';