Question

I am a Python beginner and my next project is a program in which you enter the details of your program and then select the file (I’m using Tkinter), and then the program will format the details and write them to the start of the file.

I know that you’d have to ‘rewrite’ it and that a tmp file is probably in hand. I just want to know simple ways that one could achieve adding text to the beginning of a file.

Thanks.

Answer 1

To add text to the beginning of a file, you can (1) open the file for reading, (2) read the file, (3) open the file for writing and overwrite it with (your text + the original file text).

formatted_text_to_add = 'Sample text'
with open('userfile', 'rb') as filename:
    filetext = filename.read()

newfiletext = formatted_text_to_add + '/n' + filetext
with open('userfile', 'wb') as filename:   
    filename.write(newfiletext)

This requires two I/O operations and I’m tempted to look for a way to do it in one pass. However, prior answers to similar questions suggest that trying to write to the beginning or middle of a file in Python gets complicated quite quickly unless you bite the bullet and overwrite the original file with the new text.