How to use "/" (directory separator) in both Linux and Windows in Python?

I have written a code in python which uses / to make a particular file in a folder, if I want to use the code in windows it will not work, is there a way by which I can use the code in Windows and Linux.

In python I am using this code:

pathfile=os.path.dirname(templateFile)
rootTree.write(''+pathfile+'/output/log.txt')

When I will use my code in suppose windows machine my code will not work.

How do I use "/" (directory separator) in both Linux and Windows?

Use os.path.join(). Example: os.path.join(pathfile,"output","log.txt").

In your code that would be: rootTree.write(os.path.join(pathfile,"output","log.txt"))

Use:

import os
print os.sep

to see how separator looks on a current OS.
In your code you can use:

import os
path = os.path.join('folder_name', 'file_name')

You can use os.sep:

>>> import os
>>> os.sep
'/'