How to read and write multiple files?

Question

I want to write a program for this: In a folder I have n number of files; first read one file and perform some operation then store result in a separate file. Then

Answer 1

I think what you miss is how to retrieve all the files in that directory. To do so, use the glob module. Here is an example which will duplicate all the files with extension *.txt to files with extension *.out

import glob

list_of_files = glob.glob('./*.txt')           # create the list of file
for file_name in list_of_files:
  FI = open(file_name, 'r')
  FO = open(file_name.replace('txt', 'out'), 'w') 
  for line in FI:
    FO.write(line)

  FI.close()
  FO.close()