Initialize static constant member variable in nested class
<p>Given codes in language C++</p>

<pre><code>/* file xxx.hpp */

class A
{
};

class B
{
private:
    class C
    {
        static const A a;
    };
};
</code></pre>

<p>How can I initialize the static constant member variable <code>A a</code> in nested class C?</p>
