擅长:python、mysql、java
<p>让我们使用<a href="http://docs.python.org/library/functions.html#id" rel="nofollow">id()</a>方法来获取()的内部id:</p>
<pre><code>>>> id(())
140180995895376
>>> empty_tuple = ()
>>> id(empty_tuple)
140180995895376 # same as the id of ()
>>> from copy import copy
>>> id(copy(empty_tuple))
140180995895376 # still the same as the id of ()
</code></pre>
<p>在python中()似乎被有效地存储为一个单例(至少在python>;2.6中是这样)。在</p>
<p><code>""</code>空字符串变量也有相同的行为。在</p>