Having trouble adding new strings to an existing text file

Question

I am messing around with some code to learn how to use the write and read method. So far I opened up a file called output.txt and stripped the whole line and also the last character of the line. Then I lower case all the characters that are in the output.txt. I am having trouble adding the content from variable lc to output.txt without deleting what is already in the output.txt. I tried f.write(lc) , but got an error (io.UnsupportedOperation: not readable)

Here is the code that I have so far

# open file using "with"
with open("output.txt",'w') as f:
    lines = f.read()
    
    # strip the newline and the last character from what is read in
    newLine = lines.strip()
    lastChar = lines.strip()[len(lines) - 1]

    # convert the text to lower case
    lc = newLine.lower()

    # print the lower-case text and a newline to standard output
    f.write(lc)

Do you understand what the `"w"` argument to `open` means? Do you know what the alternatives to it are? — Scott Hunter, Feb 12 '21 at 17:15
to read and write in the sime time you have to use 'r+' mode — Belhadjer Samir, Feb 12 '21 at 17:16
Please repeat your tutorial materials on file handling. Pay special attention to the f`open` modes and their uses. — Prune, Feb 12 '21 at 17:27
Thank you so much. I do understand what ```w``` and ```r``` do when using it. I did not know that ```r+``` was another alternatives. Thank you all, once again! — , Feb 12 '21 at 17:34

score 0 · Answer 1 · answered Feb 12 '21 at 17:18

you can't read from file using w mode , with'r+' mode, using write method will write the string object to the file based on where the pointer is.

# open file using "with"
with open("output.txt",'r+') as f:
    lines = f.read()
    
    # strip the newline and the last character from what is read in
    newLine = lines.strip()
    lastChar = lines.strip()[len(lines) - 1]

    # convert the text to lower case
    lc = newLine.lower()

    # print the lower-case text and a newline to standard output
    f.write(lc)

Having trouble adding new strings to an existing text file

1 Answers1