The handling of binary files is quite similar to the handling of text files. You have to open() a file when you want to access its contents, close() it when you are finished, read() from the file and write() to the file.

When you open a binary file, you have to indicate to Python that you want to handle this file in “binary mode.” You do this by adding a letter "b" to the mode argument. For instance, to open a file in “binary read” mode, the mode argument should be "rb". You can also open a file both for reading and writing; reading and writing you indicate with mode "r+", so reading and writing in binary mode is "r+b" (while it is also possible to open text files in "r+" mode, I did not indicate it in Chapter 17¹, as it seldom makes sense to open text files in this mode). Just as with text files, if you open a binary file in write-mode, with "wb", the file gets emptied. The mode "w+b" will open a file for both reading and writing, but also empties the file to start with.

When you open a file for both reading and writing, if the file pointer is not at the end of the file, when you write you actually overwrite.

You can open any file in binary mode, even text files. However, when you open text files in binary mode, you treat them like binary files, which means that Python does not do the automatic conversion of newline characters.

Closing a binary file is no different from closing a text file.

fp = open( "pc_rose.txt", "rb" )
fp.close()

Note

The code above has no output – if it does have output, that is a runtime error, meaning that “pc_rose.txt” is not available.