问题

我试图解决两个问题 - 首先，我想知道以下代码在重复调用 sleep() 函数的情况下执行所需的最短时间。我给出的代码是：

```python
from tkinter import *
from time import *
root = Tk()
canvas = Canvas(root, width=600, height=400)
canvas.pack()

a = canvas.create_line(10, 50, 20, 60, fill="#0000AA", width=2)
for i in range (0, 500):
  canvas.move(a, 1, 0.2)
  root.update()
  sleep(0.02)

起初我以为也许是 0.02，但这个答案似乎太明显了，并且没有考虑到循环。所以我有点困惑。

另外，为什么上述代码的实际执行时间会比根据 sleep() 函数调用计算出的时间更长呢？

<details>
<summary>英文:</summary>

I am trying to figure out 2 questions- Firstly, I would like to know the minimum amount of time that the following code will require to execute, given the repeated calls to the sleep() function. My given code is:

from tkinter import *
from time import *
root = Tk()
canvas = Canvas(root, width=600, height=400)
canvas.pack()

a = canvas.create_line(10, 50, 20, 60, fill="#0000AA", width=2)
for i in range (0, 500):
canvas.move(a, 1, 0.2)
root.update()
sleep(0.02)

At first I thought maybe it was 0.02, but that answer seems blatantly obvious and does not take into mind the loop. So I am a bit confused. 

Also, why is it that the actual execution of the above code will take longer than the time calculated according to the calls to the sleep() function? 

</details>


# 答案1
**得分**: 1

所以休眠会占用 10 秒（500 * 0.02），而其他调用 `canvas.move()` 和 `root.update()` 都会花费一些时间。可能不会太多，再加上一秒左右。

最简单的方法就是通过在你的代码周围加上一些计时代码来计算整个过程的时间：

```python
import datetime 

start = datetime.datetime.now()
# 你的代码放在这里
end = datetime.datetime.now() 

print(end-start)

import datetime 

start = datetime.datetime.now()
# your code here 
end = datetime.datetime.now() 

print(end-start)  

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