Convert multi-line string to UL-list

functions.php

<?php
/*
* Convert multi-line string to UL-list
* 1. Explode the multi-line string ($string) into array by the new line symbol ("\n")
* 2. Convert the array back into the string using "implode" function and append the ul and li tags.
*/
function str_to_list($str){
  return '<ul><li>' .implode('</li><li>', explode("\n", $str)). '</li></ul>';
}