TypeError: need string or buffer, list found

Question

I am working my way through Learn Python the Hard Way and am stuck on the extra credit for exercise 16. I am trying to read a file that I created using the main exercise 16. The code I wrote is as follows:

# pylint: disable-msg=C0103
""" This script reads and prints a file set from the argv """
from sys import argv

filename = argv

txt = open(filename)

print txt.read()

The file I am trying to read is:

Derp Derp
Reading this file
Will it work?

I am receiving the error: TypeError: coercing to Unicode: need string or buffer, list found but am unsure how my file is a list rather than strings.

dbr · Accepted Answer · 2012-05-12 04:02:43Z

6

To debug, try printing filename

answered May 12, 2012 at 4:02

dbr

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1 Comment

Rob Lowe Over a year ago

Wow, thanks! By printing filename, I discovered that filename was an array, or I suppose Python calls it a list? Anyways, I finished unpacking argv by changing filename = argv to script, filename = argv and everything worked swimmingly. I appreciate you teaching me to cook rather than just feeding me.

orlp · Accepted Answer · 2012-05-12 04:02:36Z

3

argv is a list of arguments to your script. The first argument is argv[1]. Try this:

from sys import argv

txt = open(argv[1])

print txt.read()

Important note: almost always the first item in a list is the 0th item, argv is an exception because the 0th argument is your script name.

answered May 12, 2012 at 4:02

orlp

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1 Comment

Rob Lowe Over a year ago

That makes sense, I didn't know thats how argv worked, I alternatively changed filename = argv to script, filename = argv. I appreciate this answer and only chose dbr's as the correct one as I'll be able to use that one as inspiration in debugging future problems I come up with.

Steve Westbrook · Accepted Answer · 2013-10-04 15:33:26Z

0

I too faced the same error but solved it with this code:

from sys import argv

txt = open(argv[1])

print txt.read()

edited Oct 4, 2013 at 15:33

Steve Westbrook

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answered Oct 4, 2013 at 15:08

pratik

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