Try telling us the what & why of what you are trying to do, rather than the how you are trying to do it.

Eg. You have a long list of floating point numbers that you wish to send to another machine and that machine expects them to be in binary form.

Or: You have a long list of numbers that you wish to save to disk, but you would prefer them to be more compact.

Or: You have a some binary data that you wish to send someone by email, and want to avoid corruption caused by the stripping of the high order bit.

Each of these is a possible scenario from what you have said and shown so far, but each requires a different solution.

A clearer question will get you better answers (and ruffle less feathers:). This is little different from what a lot of other people have already said, but maybe it is worded a little more clearly?