<?php
  $fruits = ["apple", "orange", "banana"];
  $message = implode(" / ", $fruits);
  $upperFruits = strtoupper($message);
  echo $upperFruits."<br>"; // APPLE / ORANGE / BANANA

  $newFruits = str_replace("ORANGE", "APPLE", $upperFruits);
  echo $newFruits; // APPLE / APPLE / BANANA
?>