擅长:python、mysql、java
<p>下面几行。。。你知道吗</p>
<pre><code>now = datetime.datetime.now()
if now.second != datetime.datetime.now().second:
print(now)
</code></pre>
<p>。。。仅当对<code>datetime.datetime.now()</code>的两个连续调用未在同一秒内到达时,才会打印<code>now</code>。你知道吗</p>
<p>正如您的输出所示,如果第二个增量没有在这两个调用之间落地,则有时会失败。你知道吗</p>
<h2>同步计数器</h2>
<p>与<code>datetime</code>保持同步的计数器可以这样构建。你知道吗</p>
<pre><code>import datetime
import time
precision = 0.1
previous = datetime.datetime.now()
while True:
now = datetime.datetime.now()
if previous.second != now.second:
print(now)
previous = now
time.sleep(precision)
</code></pre>
<h3>输出</h3>
<pre><code>2019-02-09 14:32:13.070108
2019-02-09 14:32:14.001819
2019-02-09 14:32:15.033610
2019-02-09 14:32:16.065388
2019-02-09 14:32:17.089926
2019-02-09 14:32:18.021687
2019-02-09 14:32:19.053557
</code></pre>