import re
import os
files = os.listdir('./')
def replaceStr(file):
with open(file, 'r', encoding='utf-8') as f:
str = f.read()
print(str)
str1 = re.sub('abd', 'cba', str)
with open(file,'w', encoding='utf-8') as f:
f.write(str1)
print(files)
for f in files:
if f.find('.txt') > -1 :
replaceStr(f)
