为什么打印功能不起作用？ 为什么 print function 没有在特定时间输出？

Question

I am trying to print the current time at a specific time, how come it is not printing what I want it to do? it is just exiting at code 0 when it get to the specific time(12:09)

from datetime import datetime as dt

now = dt.now()

current_time = now.strftime("%H:%M")

for i in range(500000000):
    if current_time == "12:09":
        print("The time is" + current_time)

Answer 1

You're only getting the time once. After you do current_time = now.strftime("%H:%M") , the current_time variable isn't going to change. If you want that, you need to move that code inside the loop so that they get run repeatedly:

for i in range(500000000):
    now = dt.now()                                # move these lines
    current_time = now.strftime("%H:%M")          # inside the loop

    if current_time == "12:09":
        print("The time is" + current_time)

Note that this code is going to thrash your CPU pretty hard, since the loop doesn't take any significant amount of time, and will likely see the same time string thousands or more times in a row. You may want to call time.sleep or a similar function to delay 30+ seconds between checks of the time (since you only care about the minutes).