Change the file extension for files in a folder?

Question

I would like to change the extension of the files in specific folder. i read about this topic in the forum. using does ideas, I have written following code and I expect that

Answer 1

You don't need to open the files to rename them, os.rename only needs their paths. Also consider using the glob module:

import glob, os

for filename in glob.iglob(os.path.join(folder, '*.grf')):
    os.rename(filename, filename[:-4] + '.las')