writing numbers in binary file

[MRAB]

eskandari wrote:
> Hi,
> I am a newbie in python. I have an data.pickle file which is
> serialized form of an "array of strings", I want to write their
> offsets in another binary file, so an C++ program can read and analyse
> them.
> But when I try to write offset (number) in binary file, it raise
> exception below in line  "offsetfile.write(offset)"
> "TypeError: argument 1 must be string or read-only buffer, not int"
> 
> I search the internet, find that all suggest converting number to
> string ---with str()---and then write string to file.
> But I shouldn't do this. because the above mentioned C++ function,
> read file with this assumption that there are numbers in file.
> So I want to know, Is there any way to produce an binary file
> containing numbers same as the way C++ does?
> Can anybody help me?
> 
You can't write ints to a file, but you can write bytestrings ('str' in
Python 2, 'bytes' in Python 3).

Use the 'struct' module to convert the int to a bytestring, and remember
to open the file as a binary file.