Carriage Return not working in IDLE?

Question

I'm trying to create a code for a countdown timer that stays in place: so that each line overwrites the previous one. This is what I have so far:

import time

def countdown(t):
    while t:
        mins, secs = divmod(t, 60)
        timeformat = "{:02d}:{:02d}".format(mins, secs)
        print(timeformat, end='\r')
        time.sleep(1)
        t -= 1
    print("That's the end! You lose...\n\n\n\n\n")
    exit()

countdown(10)

The output, however, is:

00:10
00:09
00:08
...
00:00
That's the end! You lose...

Why is the carriage return seemingly not working?

Answer 1

When \r doesn't work, try \x08 (backspace), and add the flush=True to be safe:

print('\x08' * 5 + timeformat, end='', flush=True)

Answer 2

IDLE doesn't support most control characters such as \r, \b. It is still true in 2020 (no support in Python 3.9)

\r should work if you start Python REPL in a Unix terminal or in Windows console instead.