[Tutor] Strings and file saving

Sean 'Shaleh' Perry shaleh@valinux.com
Fri, 18 Aug 2000 12:20:02 -0700 (PDT)

># read each line in the file   
> for line in in_file.readlines():
>       if string.find(line,'$')>= 0:
>#              # "print line" works well
>#              #print line
>               a = line
>#      # write the new file you created to the file "junk2.txt" 
>       out_file.write(a)
> out_file.close()
> in_file.close()

a only exists in the if block, which out_file.write() is not in.  This is
probably a logic error.  Even if a did exist, if the if was not true, you would
write an empty line or worse, the last line in a.

To ensure a does exist do the following:

a = ""
if blah:
  a = do_string_stuff

The same idea is often used to make an empty list, dictionary, etc for a loop
to populate.