How to replace all occurrences of a character except the first one in PHP using a regular expression?

Given an address stored as a single string with newlines delimiting its components like:

1 Street\nCity\nST\n12345

The goal would be to replace all newline characters except the first one with spaces in order to present it like:

1 Street
City ST 12345

I have tried methods like:

[$street, $rest] = explode("\n", $input, 2);
$output = "$street\n" . preg_replace('/\n+/', ' ', $rest);

I have been trying to achieve the same result using a one liner with a regular expression, but could not figure out how.

>Solution :

You could use a regex trick here by reversing the string, and then replacing every occurrence of \n provided that we can lookahead and find at least one other \n:

$input = "1 Street\nCity\nST\n12345";
$output = strrev(preg_replace("/(?=.*\n)\n/", " ", strrev($input)));
echo $output;

This prints:

1 Street
City ST 12345