Executing php statements from a variable

[Guardian-Mage]

Ok, on my website(It is secure and only accessible to me) I have a form with a text area. I enter php statements there, such as last_modified() so I can see the result, than I click Execute. Here is where I am stuck. I need to take the post data from the textarea and execute it as php. Any idea how I can do this?

[akitchin]

the eval() function takes a string expected to be valid PHP code and executes it.