Why Python Don't Print After A Time.sleep()?

I'm programming in python for almost 2 years and I found a really weird thing when watching some old code. import random, sys, time try: while True: print(' ', str(ran

Solution 1:

Python keeps your print outputs in a buffer and waits for the end of the line before actually displaying it. To force the display in Python 3, you can add the keyword flush=True.

import random, sys, time

try:
    while True:
        print(' ', str(random.randint(100,999)), end='', flush=True)
        time.sleep(0.01)
except:
    sys.exit()

Alternatively, you can:

• call sys.stdout.flush() after the print (Python 2-compatible);
• use the -u flag when executing the script (python -u script.py);
• set the environment variable PYTHONUNBUFFERED to TRUE.

Solution 2:

This answer Python sleep() inhibit print with comma? suggests adding sys.stdout.flush() between the print and the sleep. Tested it - works.

Solution 3:

Which version of PYTHON are you using? I was able to run your code in my PC where I am using PYTHON 3.7 in PYCHARM 2019.2.4. It also ran successfully on PYTHON 3.7.5 shell

Solution 4:

Try this:

import random, sys, time
try:
    while True:
        print(' ', str(random.randint(100,999)), end='', flush=True)
        time.sleep(1)
except:
    sys.exit()

Solution 5:

This is because you have a while True clause that's looping forever, Causing it loop recursively infinitely.

Here is the updated code

import random, sys, time

try:
    whileTrue:
        print(' ', str(random.randint(100,999)), end='')
        time.sleep(0.01)
        breakexcept:
    sys.exit()

I added a break statement to move to get out of the loop.