python3终端输出时间

引自:https://stackoverflow.com/questions/5852981/python-how-do-i-display-a-timer-in-a-terminal 

The simplest way is as follows.

import time
import sys

for remaining in range(10, 0, -1):
    sys.stdout.write("\r")
    sys.stdout.write("{:2d} seconds remaining.".format(remaining)) 
    sys.stdout.flush()
    time.sleep(1)

sys.stdout.write("\rComplete!            \n")

"\r" returns the text cursor to the beginning of the line, so that you can overwrite what you're previously written. Because typically output isn't written until a newline ("\n"), you need to manually .flush() the output stream.

Because the line isn't being cleared, we need to ensure that each new line of output is long enough to cover up the existing line.

The curses module has tools for more advanced terminal output, but is more complicated to use.

自己的程序:

import datetime
import time, sys
for i in range(100):
    now = datetime.datetime.now() 
    sys.stdout.write("\r")
    sys.stdout.write("{}".format(str(now)[:-7]))
    sys.stdout.flush()
    time.sleep(1)