Writing a binary file in Python?

Started by
8 comments, last by Fruny 17 years, 10 months ago
My attempts using write() have failed miserably. Do I need to get a specific library?
Advertisement
You might want to use the struct module.
"Debugging is twice as hard as writing the code in the first place. Therefore, if you write the code as cleverly as possible, you are, by definition, not smart enough to debug it." — Brian W. Kernighan
Could you post some source code? Without seeing it, my first guess would be that you aren't opening the file in binary mode.

f = file("file.bin", "wb") # w: write, b: binary
f.write(data)
Quote:Original post by smr
Could you post some source code? Without seeing it, my first guess would be that you aren't opening the file in binary mode.

Actually, opening a file in "binary" mode is only meaningful under Windows, for starters. Secondly, file.write will always perform a character-mode write. Now, you can use it to write the data in binary format, but you have to pack that data into a string first.

The struct module exists for this specific reason. Use it. [smile]
Quote:Original post by Oluseyi
Quote:Original post by smr
Could you post some source code? Without seeing it, my first guess would be that you aren't opening the file in binary mode.

Actually, opening a file in "binary" mode is only meaningful under Windows, for starters. Secondly, file.write will always perform a character-mode write. Now, you can use it to write the data in binary format, but you have to pack that data into a string first.

The struct module exists for this specific reason. Use it. [smile]


I also assume he's using windows :D

I didn't mention struct since Fruny had already and didn't want to steal his thunder.
I had never heard of the struct-module, before: I'll go investigate it.
You might also be interested in the cPickle module if this is for object serialization. If this data is only going to be accessed from your python program, it's much easier:
import cPickleclass Game(object):    ...game = Game()cPickle.dump(game, open("game.dat", "w"))...game = cPickle.load(open("game.dat"))


[Edited by - bytecoder on June 7, 2006 5:40:27 PM]
bytecoder, you are a saint. I very much appreciate your graciousness, here.
How do I set the endian of a file?
Quote:Original post by Anonymous Poster
How do I set the endian of a file?


Files have no endianness. The data does. See the struct module documentation.
"Debugging is twice as hard as writing the code in the first place. Therefore, if you write the code as cleverly as possible, you are, by definition, not smart enough to debug it." — Brian W. Kernighan

This topic is closed to new replies.

Advertisement