Read a zip an write it to an other file python

Question

I want to read a file and write it back out. Here's my code:

   file = open( zipname , 'r' )
   content =  file.read() 
   file.close()

   alt = open('x.zip', 'w')
   alt.write(content )
   alt.close()

This doesn't work, why?????

Edit:

The rewritten file is corrupt (python 2.7.1 on windows)

Answer 1

Read and write in the binary mode, 'rb' and 'wb':

f = open(zipname , 'rb')
content =  f.read() 
f.close()

alt = open('x.zip', 'wb')
alt.write(content )
alt.close()

The reason the text mode didn't work on Windows is that the newline translation from '\r\n' to '\r' mangled the binary data in the zip file.

Answer 2

From this bit of the manual:

On Windows, 'b' appended to the mode opens the file in binary mode, so there are also modes like 'rb', 'wb', and 'r+b'. Python on Windows makes a distinction between text and binary files; the end-of-line characters in text files are automatically altered slightly when data is read or written. This behind-the-scenes modification to file data is fine for ASCII text files, but it’ll corrupt binary data like that in JPEG or EXE files. Be very careful to use binary mode when reading and writing such files. On Unix, it doesn’t hurt to append a 'b' to the mode, so you can use it platform-independently for all binary files.