Reddit.com: Where can I find a free place to edit PHP code and see the results?

In this recent post to Reddit.com, the question is asked "Where can I find a free place to edit PHP code and see the results?"

Hey everyone,
Recently I was tasked with coming up with some code for an possible job opportunity. I'm wondering if anyone could point me to a place where I can easily write and edit PHP code and see the actual program run.

Suggestions from the comments include:

• Codepad.org
  
• Ideone.com
  
• The built-in webserver for PHP 5.4.x
  
• Ignite.io