This question already has answers here:
Difference between r+ and w+ in fopen()
(7 answers)
Closed 6 years ago.
I tried to use both of them opening a file but got the same result.
w+ is supposed to create a new file if it doesn't exist while r+ not.
Is this the only difference?
For example, this is an initial file file.txt
Line 1
Line 2
Line 3
1) file.txt after implementing of r+ mode (writing the word "hello")
hello
2) file.txt after implementing of w+ mode
hello
I guessed that r+ would append an input to the beginning of the file.
EDITED:
So, the 1st difference is about creating a file that doesn't exist and the 2nd difference is that r+ overwrites while w+ truncates, right? (than the question arises whether overwriting and truncating are the same concepts or not)
Remove file.txt first and you'll understand the difference.
w+ will create the file.
Related
This question already has answers here:
Confused by python file mode "w+" [duplicate]
(11 answers)
Closed 6 months ago.
I am using VSC for writing python scripts to read/write file. I am able to write file using the below code:
with open("score_card.txt", mode="w+") as file_data:
file_data.write("23")
but when trying to read the file using the below code:
with open("score_card.txt", mode="w+") as file_data:
print(file_data.read())
it is not giving anything in the terminal.
You need to open the file in read mode. Here's an example:
with open("score_card.txt", mode="r") as file_data:
print(file_data.read())
You can learn more about the open function modes here https://docs.python.org/3/library/functions.html#open
An important thing to remember is that the w+ mode is for truncating and writing. This means that it will wipe the file contents, so when you try to read it, there is nothing in the file. You should use mode='r' on all files that you don't intend to edit.
This question already has answers here:
How to open a file for both reading and writing?
(4 answers)
Closed 2 years ago.
How can I use the 'r' and 'w' at the same time?
Hi I want to know if I can use 'r' and 'w' at the same time, the following is an example
# Example
with open('txt.txt', 'w') as t:
t.write('Hello World')
t.readable()
eg = t.readlines()
When I write this down it will create the txt file but it gives me an error.
I Want to know how to use 'r' and 'w' at the same time
Please help me
I am suffering
I need help
You use r+. The r character means read-only, w means write-only, r+ means read and write.
Just keep in mind that you'll probably need to manage the file pointers (where your current position is) when switching between read and write operations.
This question already has answers here:
How do I append to a file?
(13 answers)
Closed 8 years ago.
This code actually overwrite the pre-existing content of out.txt, is there a way to make it print in the next line ?
with open(r'C:\out.txt', "w") as presentList:
print("Hello", file=presentList)
Use "a" instead of "w".
This appends new text at the end.
I think you'll want to open with "r+" instead (opening with "w" overwrites the file!). If you aren't partial to using with, you can do
f = open("C:/out.txt","r+")
f.readlines()
f.write("This is a test\n")
f.close()
The f.readlines() will ensure that you write to the end of the file instead of overwriting the first line if you need to write more. As the other person said, you can also open with "a" too
This question already has answers here:
How do I append to a file?
(13 answers)
Closed 8 years ago.
I need to add my program's outputs to a saved file every time I run the program without overwriting the previous outputs.
This is how I'm writing to a file now:
lead.write(str(alldates))
Any ideas?
Here, you should open the file in append mode:
append_text = str(alldates)
with open('my_file.txt', 'a') as lead:
lead.write(append_text)
There are lots of specialised ways to open files for different purposes, and you can read about them in the documentation.
You should open the file in append mode.
This question already has answers here:
Difference between modes a, a+, w, w+, and r+ in built-in open function?
(9 answers)
Closed 9 years ago.
As in, when opening a file with open(), why do we have modes 'r+', 'w+', 'a+'? Surely mode 'a' does the same job? I'm especially confused by the difference between modes 'a' and 'a+' - could someone explain where they differ and, if possible, when one should use one or the other?
The opening modes are exactly the same that C fopen() std library function.
The BSD fopen manpage defines them as follows:
``a'' Open for writing. The file is created if it does not exist. The
stream is positioned at the end of the file. Subsequent writes
to the file will always end up at the then current end of file,
irrespective of any intervening fseek(3) or similar.
``a+'' Open for reading and writing. The file is created if it does not
exist. The stream is positioned at the end of the file. Subse-
quent writes to the file will always end up at the then current
end of file, irrespective of any intervening fseek(3) or similar.
The only difference between a and a+ is that a+ allows reading of files.
See this post for more info.
Quoted from the Python 2.7 tutorial:
mode can be 'r' when the file will only be read, 'w' for only writing
(an existing file with the same name will be erased), and 'a' opens
the file for appending; any data written to the file is automatically
added to the end. 'r+' opens the file for both reading and writing.
The mode argument is optional; 'r' will be assumed if it’s omitted.
'a' opens the file in write (append at end of file) mode, while 'r+' opens it in both read and write (insert at start of file).