擅长:python、mysql、java
<p>如果要确定列表的长度/大小,我想您应该使用<code>len(a)</code>,而不是{<cd2>}。<code>a.count()</code>实际上需要一个参数。它统计一个值的出现次数。例如:</p>
<pre><code>a = [2, 6, 2, 1, 5, 3, 9, 5]
print a.count(5) #should display 2 because there are two elements with a value of 5
print a.count(3) #should display 1 because there is only one element with a value of 3
</code></pre>