cStringIO & write error?

[ingo]

When I do:

from StringIO import StringIO
f=open('file.dat', 'r+b')
ff=StringIO(f.read(-1))
ff.seek(0,0)
ff.write(chr(123))

all is ok. But when I import from cStringIO I get an error:

line 311, in RunScript

    exec codeObject in __main__.__dict__

  File "D:\Ingo\PyScript\df3\Script1.py", line 5, in ?

    ff.write(chr(123))

AttributeError: write

What am I doing wrong?


TIA,
Ingo

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