How to write to .txt files in Python 3

Question

I have a .txt file in the same folder as this .py file and it has this in it:

cat\n dog\n rat\n cow\n 

How can I save a var (var = 'ant') to the next line of the .txt file?

Answer 1

Open the file in append mode and write a new line (including a \n line separator):

with open(filename, 'a') as out:     out.write(var + '\n') 

This adds the line at the end of the file after all the other contents.

Answer 2

Just to be complete on this question:

You can also use the print function.

with open(filename, 'a') as f:     print(var, file=f) 

The print function will automatically end each print with a newline (unless given an alternative ending in the call, for example print(var, file=f, end='') for no newlines).