how does this Implicit conversion happen?
<p>how does this Implicit conversion happen? </p>

<pre><code>class A {};
class B { public: B (A a) {} };

A a;
B b=a;
</code></pre>

<p>class B has a constructor B(A a) takes object a as a object,but inside the constructor of B, it does nothing. so how does this happens?  </p>
