I am attempting to output a new txt file but it come up blank. I am doing this
my_file = open("something.txt","w")
#and then
my_file.write("hello")
Right after this line it just says 5 and then no text comes up in the file
What am I doing wrong?
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You can share the exact code here. The same thing works on my system. Try to close the file by using my_file.close().shivam mitra– shivam mitra2015-09-10 15:24:17 +00:00Commented Sep 10, 2015 at 15:24
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1How are you checking that text is output to the file, and how are you running this?Two-Bit Alchemist– Two-Bit Alchemist2015-09-10 15:27:40 +00:00Commented Sep 10, 2015 at 15:27
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4 Answers
You must close the file before the write is flushed. If I open an interpreter and then enter:
my_file = open('something.txt', 'w')
my_file.write('hello')
and then open the file in a text program, there is no text.
If I then issue:
my_file.close()
Voila! Text!
If you just want to flush once and keep writing, you can do that too:
my_file.flush()
my_file.write('\nhello again') # file still says 'hello'
my_file.flush() # now it says 'hello again' on the next line
By the way, if you happen to read the beautiful, wonderful documentation for file.write, which is only 2 lines long, you would have your answer (emphasis mine):
Write a string to the file. There is no return value. Due to buffering, the string may not actually show up in the file until the flush() or close() method is called.
2 Comments
zstewart
This answer is sufficient, though if you want to write the file as you go (write some, make sure it's on disk, write some more later), you can also use flush.
Two-Bit Alchemist
Sorry, yes, I am going to expand the answer -- just looking for a decent place to link to in the docs.
If you don't want to care about closing file, use with:
with open("something.txt","w") as f:
f.write('hello')
Then python will take care of closing the file for you automatically.
Comments
As Two-Bit Alchemist pointed out, the file has to be closed. The python file writer uses a buffer (BufferedIOBase I think), meaning it collects a certain number of bytes before writing them to disk in bulk. This is done to save overhead when a lot of write operations are performed on a single file.
Also: When working with files, try using a with-environment to make sure your file is closed after you are done writing/reading:
with open("somefile.txt", "w") as myfile:
myfile.write("42")
# when you reach this point, i.e. leave the with-environment,
# the file is closed automatically.
Comments
The python file writer uses a buffer (BufferedIOBase I think), meaning it collects a certain number of bytes before writing them to disk in bulk. This is done to save overhead when a lot of write operations are performed on a single file. Ref @m00am
Your code is also okk. Just add a statement for close file, then work correctly.
my_file = open("fin.txt","w")
#and then
my_file.write("hello")
my_file.close()
2 Comments
m00am
True, this works well if everything goes according to plan. The
with provides additional safety if something goes wrong before close() can be called, so you don't end up with an open file. stackoverflow.com/questions/17577137/…
Sakib Ahammed
Hmm. I don't know about this explanation. hanks :)