If I want to try out something new in Ruby or Javascript, I love getting immediate feedback from irb or the JS console in Firebug.
Is there anything like that for PHP?
Update
As @bernie pointed out, such tools are called REPLs – “Read-eval-print loop”
Run
php -ain the command-line. But this does not work on Windows.For Windows, you may want to try phpa-norl.