I hope this isn't some school assignment question trollling...

You're leaving a lot of information out of the question, but one can guess that you want to do huffman decoding.

I assume that your huffman tree has nodes with methods left,right, value. So $node->value() is probably going to return a binary number - I would imagine in fact that your put_stream method is where this should go but basically you just want to do: chr(oct("0b".$cur_node->value)); See 15577 for info on converting to decimal from binary. Some error checking to make sure you aren't producing a number > 255 before calling chr would be in order too.

Can't do a whole lot else to help without some more info.

Update: Course as kal says, need to know the endianess of your data otherwise that won't work.