Python error message io.UnsupportedOperation: not readable
Python 3.xFilePython 3.x Problem Overview
I made a simple program but It shows the following error when I run it:
line1 = []
line1.append("xyz ")
line1.append("abc")
line1.append("mno")
file = open("File.txt","w")
for i in range(3):
file.write(line1[i])
file.write("\n")
for line in file:
print(line)
file.close()
It shows this error message:
> File "C:/Users/Sachin Patil/fourth,py.py", line 18, in
> for line in file:
>
> UnsupportedOperation: not readable
Python 3.x Solutions
Solution 1 - Python 3.x
You are opening the file as "w", which stands for writable.
Using "w" you won't be able to read the file. Use the following instead:
file = open("File.txt", "r")
Additionally, here are the other options:
"r" Opens a file for reading only.
"r+" Opens a file for both reading and writing.
"rb" Opens a file for reading only in binary format.
"rb+" Opens a file for both reading and writing in binary format.
"w" Opens a file for writing only.
"a" Open for writing. The file is created if it does not exist.
"a+" Open for reading and writing. The file is created if it does not exist.
Solution 2 - Python 3.x
Use a+ to open a file for reading, writing and create it if it doesn't exist.
> a+ Opens a file for both appending and reading. The file pointer is at > the end of the file if the file exists. The file opens in the append > mode. If the file does not exist, it creates a new file for reading > and writing. -Python file modes
with open('"File.txt', 'a+') as file:
print(file.readlines())
file.write("test")
Note: opening file in a with block makes sure that the file is properly closed at the block's end, even if an exception is raised on the way. It's equivalent to try-finally, but much shorter.
Solution 3 - Python 3.x
There are few modes to open file (read, write etc..)
If you want to read from file you should type file = open("File.txt","r"), if write than file = open("File.txt","w"). You need to give the right permission regarding your usage.
more modes:
- r. Opens a file for reading only.
- rb. Opens a file for reading only in binary format.
- r+ Opens a file for both reading and writing.
- rb+ Opens a file for both reading and writing in binary format.
- w. Opens a file for writing only.
- you can find more modes in here
Solution 4 - Python 3.x
This will let you read, write and create the file if it don't exist:
f = open('filename.txt','a+')
f = open('filename.txt','r+')
Often used commands:
f.readline() #Read next line
f.seek(0) #Jump to beginning
f.read(0) #Read all file
f.write('test text') #Write 'test text' to file
f.close() #Close file
Solution 5 - Python 3.x
Sreetam Das's table is nice but needs a bit of an update according to w3schools and my own testing. Unsure if this due to the move to python 3.
"a" - Append - will append to the end of the file and will create a file if the specified file does not exist.
"w" - Write - will overwrite any existing content and will create a file if the specified file does not exist.
"x" - Create - will create a file, returns an error if the file exist.
I would have replied directly but I do not have the rep.