在原有的文件上，修改替换，并放到新的文件里
old = open('day','r')new = open('new_day','w')
old_replace = input('please replace content:')
new_replace = input('please new replace content:')for i in old: if old_replace in i:
i = i.replace(old_replace,new_replace) new.write(i)
old.close()new.close()
