php -r code example

Example 1: php

<?php 
echo "Hello, World!"; 
?>

Example 2: \r in php

They're "carriage return" and "line feed" respectively. Typically on Windows, you need both together to represent a line terminator: "\r\n" whereas on most (all?) Unix systems, "\n" is enough.

Example 3: basic php

<?php
  
  // This is a comment
  
  echo 'Hello, World!';
  
  // And this outputs Hello, World!
  
?>