[Tutor] reset password program

[Hugo Arts]

On Fri, Dec 16, 2011 at 11:49 PM, ADRIAN KELLY <kellyadrian at hotmail.com> wrote:
> thanks dave,
> just tried writing to file for the first time
>
> def main():
>  outfile.write('Hello this is a test')
>  outfile.close()
> main()
>
> error, globalname outfile is not defined, do i need to import function to
> get this working?
>

A lot of stuff is missing here. let's get back to basics. What is
outfile? It's a variable. So, where does it come from? well, right
now, you just sort of magically conjure it up out of nowhere, which is
why python is complaining ("not defined" is the python telling you
"you never told me what this thing is"). So, we want the variable
outfile to point to a file object. Making a file object is very
simple, just call the open() function. You don't have to import
open(), it's a builtin, which means it's always available to you:

outfile = open('file_name.txt', 'w')

open takes two arguments. The first one is the filename, the second is
the mode in which the file is to be opened. Basically, 'r' is for
reading, 'w' for writing (this mode will delete existing data in the
file, if any), and 'a' is appending. You can add a 'b' for opening in
binary mode, and a '+' for opening the file for updating.

Now we have a file object, and we can use the write() method on it as
you have done above (make sure not to forget close(), it's good
practice). That should get you started. There's a good bit of theory
behind saving passwords securely (you don't usually want everyone to
be able to open the file and read the passwords, basically), but I
won't get into that right now. If you're ready for that, you might
want to check out hashlib