TypeError: expected a character buffer object - while trying to save integer to textfile

Question

I'm trying to make a very simple 'counter' that is supposed to keep track of how many times my program has been executed.

First, I have a textfile that only includes one character: 0

Then I open the file, parse it as an int, add 1 to the value, and then try to return it to the textfile:

f = open('testfile.txt', 'r+')
x = f.read()
y = int(x) + 1
print(y)
f.write(y)
f.close()

I'd like to have y overwrite the value in the textfile, and then close it.

But all I get is TypeError: expected a character buffer object.

Edit:

Trying to parse y as a string:

f.write(str(y))

gives

IOError: [Errno 0] Error

Lev Levitsky · Accepted Answer · 2012-03-20 12:50:51Z

76

Have you checked the docstring of write()? It says:

write(str) -> None. Write string str to file.

Note that due to buffering, flush() or close() may be needed before the file on disk reflects the data written.

So you need to convert y to str first.

Also note that the string will be written at the current position which will be at the end of the file, because you'll already have read the old value. Use f.seek(0) to get to the beginning of the file.`

Edit: As for the IOError, this issue seems related. A cite from there:

For the modes where both read and writing (or appending) are allowed (those which include a "+" sign), the stream should be flushed (fflush) or repositioned (fseek, fsetpos, rewind) between either a reading operation followed by a writing operation or a writing operation followed by a reading operation.

So, I suggest you try f.seek(0) and maybe the problem goes away.

edited Mar 20, 2012 at 12:50

answered Mar 20, 2012 at 12:45

Lev Levitsky

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Burhan Khalid · Accepted Answer · 2012-03-20 12:54:53Z

9

from __future__ import with_statement
with open('file.txt','r+') as f:
    counter = str(int(f.read().strip())+1)
    f.seek(0)
    f.write(counter)

answered Mar 20, 2012 at 12:54

Burhan Khalid

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salah Laaroussi · Accepted Answer · 2014-05-17 08:30:51Z

1

Just try the code below:

As I see you have inserted 'r+' or this command open the file in read mode so you are not able to write into it, so you have to open file in write mode 'w' if you want to overwrite the file contents and write new data, otherwise you can append data to file by using 'a'

I hope this will help ;)

f = open('testfile.txt', 'w')# just put 'w' if you want to write to the file 

x = f.readlines() #this command will read file lines

y = int(x)+1

print y
z = str(y) #making data as string to avoid buffer error
f.write(z)

f.close()

answered May 17, 2014 at 8:30

salah Laaroussi

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