Python Help? Just some simple stuff :)

[mattonfire]

Hiya, does anyone know how to read specific lines in a text file using python?

 

Here is the python file - Barcode Checker - Task 3.py

Here is the text file - barcodes.txt

 

In the barcodes.txt under the item name is the stock I want to make it so I can change the integers so if they buy 5 Titan X's it'll take off 5 from the txt but they can't take more than what's there.

[Sauron]

with readline()

[mattonfire]

2 minutes ago, Sauron said:

with readline()

Thanks dude, thanks for the link to a good website too

[Sauron]

Just now, mattonfire said:

Thanks dude, thanks for the link to a good website too

np ^^

[mattonfire]

45 minutes ago, Sauron said:

np ^^

Heya, do you know how to do the same as in write in a specific line "writelines()" works kinda differently, I need it so it would totally overwrite the previous line and write it with the new data.

[mattonfire]

Please anyone, I gotta get this done by tonight! :(((

[Sauron]

1 hour ago, mattonfire said:

Heya, do you know how to do the same as in write in a specific line "writelines()" works kinda differently, I need it so it would totally overwrite the previous line and write it with the new data.

I think you need a separate funcion to delete the line, then use write or writeline to write it again. Maybe this can help

 

http://www.afterhoursprogramming.com/tutorial/Python/Writing-to-Files/

[mattonfire]

11 hours ago, Sauron said:

I think you need a separate funcion to delete the line, then use write or writeline to write it again. Maybe this can help

 

http://www.afterhoursprogramming.com/tutorial/Python/Writing-to-Files/

But I don't know how to writeline to a specific line, deleting the line is fine.

[Sauron]

6 minutes ago, mattonfire said:

But I don't know how to writeline to a specific line, deleting the line is fine.

Maybe linecache?

[mattonfire]

26 minutes ago, Sauron said:

Maybe linecache?

Still only for reading.

[Hawx]

Try 

        with open("barcodes.txt", "w") as f:
            f.writelines(lines)

Before writing, you can modify lines with lines[0] = "this is a line" etc

 

Also that while loop is a tad messy, what's with the unnecessary try/except statement, and the super long "if again == "yes"" etc instead of formatting the input with ".lower()"?