val = val.encode('hex')

That's the crucial line -- it's returning a new integer, which you are re-binding to val. If you then did:

  val = val + 1

you'd be fine, and could then write val back to your file :-)

On Thu, 20 Aug 2009 14:08:34 -0700, Matthias Güntert <matzeguent...@gmx.de> wrote:

Hello guys

I would like to read a hex number from an ASCII file, increment it and
write it back.
How can this be performed?

I have tried several approaches:

my file serial.txt contains: 0C

----------------------------------
f = open('serial.txt', 'r')
val = f.read()
val = val.encode('hex')
print val
----------------------------------
--> 3043

----------------------------------
f = open('serial.txt', 'r')
val = f.read()
print val
val = val+1
----------------------------------
--> TypeError: cannot concatenate 'str' and 'int' objects

----------------------------------
f = open('serial.txt', 'rb')
val = f.read()
val = val + 1
----------------------------------
--> TypeError: cannot concatenate 'str' and 'int' objects


hm....




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Rami Chowdhury
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