find all subdomains in a string using php - php

Question

hello here is my html :
<div>
hello.domain.com
holla.domain.com
stack.domain.com
overflow.domain.com </div>
I want to return an array with : hello, holla, stack,overflow
then I have this https://hello.domain.com/c/mark?lang=fr
I want to return the value : mark
I know it should be done with regular expressions. As long as I know how to do it regular expression or not it will be good. thank you

Answer 1

Part 1: Subdomains
$regex = '~\w+(?=\.domain\.com)~i';
preg_match_all($regex, $yourstring, $matches);
print_r($matches[0]);
See the matches in the regex demo.
Match Array:
[0] => hello
[1] => holla
[2] => stack
[3] => overflow
Explanation
The i modifier makes it case-insensitive
\w+ matches letters, digits or underscores (our match)
The lookahead (?=\.domain\.com) asserts that it is followed by .domain.com
Part 2: Substring
$regex = '~https://hello\.domain\.com/c/\K[^\s#?]+(?=\?)~';
if (preg_match($regex, $yourstring, $m)) {
$thematch = $m[0];
}
else { // no match...
}
See the match in the regex demo.
Explanation
https://hello\.domain\.com/c/ matches https://hello.domain.com/c/
The \K tells the engine to drop what was matched so far from the final match it returns
[^\s#?]+ matches any chars that are not a white-space char, ? or # url fragment marker
The lookahead (?=\?) asserts that it is followed by a ?

Answer 2

Although I am not sure where you are trying to take this.
$input = 'somthing.domain.com';
$string = trim($input, '.domain.com');
may help you.

Answer 3

About the second part of your question, you can use the parse_url function:
$yourURL = 'https://hello.domain.com/c/mark?lang=fr';
$result = end(explode('/', parse_url($yourURL, PHP_URL_PATH)));

Answer 4

For the second part of your question (extract part of a URL) others have answered with a highly specific regex solution. More generally what you are trying to do is parse a URL for which there already exists the parse_url() function. You will find the following more flexible and applicable to other URLs:
php > $url = 'https://hello.domain.com/c/mark?lang=fr';
php > $urlpath = parse_url($url, PHP_URL_PATH);
php > print $urlpath ."\n";
/c/mark
php > print basename($urlpath) . "\n";
mark
php > $url = 'ftp://some.where.com.au/abcd/efg/wow?lang=id&q=blah';
php > print basename(parse_url($url, PHP_URL_PATH)) . "\n";
This assumes that you are after the last part of the URL path, but you could use explode("/", $urlpath) to access other components in the path.