Class non-static method pointer to global function
<p>I'm trying to point a class method to a global function, i've seen <a href="https://stackoverflow.com/questions/6005024/c-class-member-pointer-to-global-function">this</a><br>
but how i can't do it without instance?.</p>

<p>Consider this:</p>

<pre><code>class x
{
    public:
        int(x::*GetVal)(int);
};

int RtX(int a)
{
    return a * 4;
}

// declaration
int(x::*GetVal)(int) = (int(x::*)(int))&amp;::Rtx; // :: global? // error

int main()
{
    x a;
    cout &lt;&lt; (a.*GetVal)(4) &lt;&lt; endl; 
}
</code></pre>

<p>This returns me the error:</p>

<blockquote>
  <p>[Error] invalid cast from type 'int (<em>)(int)' to type 'int
  (x::</em>)(int)'</p>
</blockquote>