Python inserting variable string as file name

I’m trying to create a file with a unique file name for every time my script runs. I am only intending to do this to every week or month. so I chose to use the date for the file name.

f = open('%s.csv', 'wb') %name

is where I’m getting this error.

Traceback (most recent call last):
File "C:UsersUserworkspacenew3stjohnsinvoicesBabblevoiceInvoiceswpath.py", line 143,      in <module>
f = open('%s.csv', 'ab') %name
TypeError: unsupported operand type(s) for %: 'file' and 'str'

it works if I use a static filename, is there an issue with the open function, that means you can’t pass a string like this?

name is a string and has values such as :

31/1/2013BVI

Many thanks for any help.

Answer

You need to put % name straight after the string:

f = open('%s.csv' % name, 'wb')

The reason your code doesn’t work is because you are trying to % a file, which isn’t string formatting, and is also invalid.