Python IOError: File not open for reading

Question

I get an error when I try to open a file in Python. Here is my code :

>>> import os.path
>>> os.path.isfile('/path/to/file/t1.txt')
>>> True
>>> myfile = open('/path/to/file/t1.txt','w')
>>> myfile
>>> <open file '/path/to/file/t1.txt', mode 'w' at 0xb77a7338>
>>> myfile.readlines()
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
IOError: File not open for reading

I also tried:

for line in myfile:
    print(line)

and I got the same error. Does anybody know why this error occurs?

Martijn Pieters · Accepted Answer · 2012-11-09 14:13:12Z

47

You opened the file for writing by specifying the mode as 'w'; open the file for reading instead:

open(path, 'r')

'r' is the default, so it can be omitted. If you need to both read and write, use the + mode:

open(path, 'w+')

w+ opens the file for writing (truncates it to 0 bytes) but also lets you read from it. If you use r+ it is also opened for both reading and writing, but won't be truncated.

If you are to use a dual-mode such as r+ or w+, you need to familiarize yourself with the .seek() method too, as using both reading and writing operations will move the current position in the file and you'll most likely want to move that current file position explicitly between such operations.

See the documentation of the open() function for further details.

edited Nov 9, 2012 at 14:13

answered Nov 9, 2012 at 14:05

Martijn Pieters

1.1m326 gold badges4.2k silver badges3.4k bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

user395760 Over a year ago

Also note that 'r' is the default mode and doesn't have to be given explicitly.

Martijn Pieters Over a year ago

@delnan: I've made it explicit in the answer.

Alireza Over a year ago

@MartijnPieters: Thank you, That was a simple mistake

Matt Seymour · Accepted Answer · 2012-11-09 14:10:58Z

1

Simple mistake if you think about it it. In your code you are doing:

myfile = open('/path/to/file/t1.txt','w')

Which specifies it is for writing, what you need to do is set this to r which is for read

myfile = open('/path/to/file/t1.txt','r')

answered Nov 9, 2012 at 14:10

Matt Seymour

9,4437 gold badges64 silver badges106 bronze badges

Collectives™ on Stack Overflow

Python IOError: File not open for reading

2 Answers 2

3 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

3 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related