instagram regex

def instacheck(name)

  unless /[a-z0-9._]{,30}/.match(name)
    return false
  end

  if /\.\./.match(name)
    return false
  end

  if /^\d+$/.match(name)
    return false
  end

  if /^\./.match(name)
    return false
  end

  true
end

@verstecken You would pick one of several options in this thread and paste the regex into your function as per its manual page: https://www.php.net/manual/en/function.preg-match.php

Thanks, @technion I tried that before and didn't get it.
You will need to delimit your pattern with for example '/' in preg_match() and it is not explained on the functions manual website. Maybe a basic to know? Well, that`s why I asked here, because pasting the regex from above did not work straight. I found some info here: https://infoheap.com/php-regex-delimiter-examples/

If you want to get the username out of an instagram or twitter URL, in PHP, this works well:

$url = "https://instagram.com/some.username";
$pattern = "/(?:(?:http|https):\/\/)?(?:www\.)?(?:instagram\.com|instagr\.am|twitter\.com)\/([A-Za-z0-9-_\.]+)/im";

preg_match($pattern, $url, $matches);
echo $matches[1]; // Yeah! This returns "some.username"

My regex did no include any such characters. I can't comment on subsequent advice from anyone else. My code already checked for leading dots and did not fail any tests people brought up relating to someone elses code.