integer greater or equal to 65536

Regular expression ^(?:https?:)?(?:\/\/)?(?:+@)?(?:www\.)?(+) used below extracts domain with subdomains out of a full url. It skips protocol (ex: https:), "//", "@", www subdomain and then captures everything (ex: domain) before ":" or "/" or end of line.

matches the http portion of a url, both http:// and https://, and also matches the www. portion if that is included.

substring

Check if first char is 0 followed by 9 digits

Check if there's consecutive chars