Variable problems

Hi. I've sort of programmed myself into a corner on a recent projekt i've been working on. This is the last part of the projekt, and i sure hope someone can help me on this one. Scenario is: I want to read a HTML file containing PHP variables into a string, then replace the variables with text from another array. I.e a simple str_replace() would do the trick, unless it was a variable i would want to change. The strings i'm trying to replace is <?=$output[?]?> Where ? can be anything from 0 to whatever.. Anyone know a solution to this? /Micke