代码：

#！ python3

# stopwatch.py - A simple stopwatch program.

import time

# Display the program's instructions.

print('Press ENTER to begin. Afterwards, press ENTER to "click" the stopwatch. \

Press Ctrl-C to quit.')

input()      # press Enter to begin

print('Started.')

startTime = time.time()  # get the first lap's start time

lastTime = startTime

lapNum = 1  

 
# Start tracking the lap times.

try:

 while True:

  input()

  lapTime = round(time.time() - lastTime, 2)

  totalTime = round(time.time() - startTime, 2)

  print('Lap #%s: %s (%s)' % (lapNum, totalTime, lapTime), end='')

  lapNum += 1

  lastTime = time.time() # reset the last lap time

except KeyboardInterrupt:

 # Handle the Ctrl-C exception to keep its error message from displaying.

 print('\nDone.')