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POAccessing a member variable's address in derived class.Behavior change when member is having different access specifier
 

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  1. POAccessing a member variable's address in derived class.Behavior change when member is having different access specifier
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    <p>I have a base class A and derived class B</p> <p>class B is derived from A as public </p> <p>I want to access the member variable's address if <strong>A is class a is member variable</strong> </p> <p>I am observing different behavior when i am using protected and public access specifier.</p> <p>When member a of class A is <strong>protected</strong> in this case i am getting:</p> <p><code>cout&lt;&lt;&amp;A::a &lt;&lt; endl;</code> throwing me an compiler error..</p> <p>but <code>cout&lt;&lt;&amp;(A::a)&lt;&lt;endl;</code> is valid and giving me proper result.</p> <p>and When member a of class A is <strong>public</strong> in this case i am getting: </p> <p>Why this behavior?</p> <p>Here is the full code :</p> <pre><code>#include &lt;iostream&gt; using namespace std; class A { protected: int a; void fun() { cout&lt;&lt;"A's fun"&lt;&lt;endl; } public: A(int Aarg):a(Aarg) { cout &lt;&lt; "A's construction done" &lt;&lt;endl; } }; class B: public A { protected: int b; public: void fun() { cout &lt;&lt; "B's fun"&lt;&lt;endl; } B(int As, int Bs):A(As), b(Bs) { std::cout&lt;&lt;"B's Construction Done" &lt;&lt;std::endl; } void show() { A::fun(); //cout &lt;&lt; a &lt;&lt; endl; cout&lt;&lt;&amp;A::a &lt;&lt; endl; //compilation error } }; int main() { B(10,20).show(); return 0; } </code></pre> <p><strong>Now there is a undefined behavior i am able to observe:</strong></p> <p>If i make my member variable a in class A as public then there will not be any compilation error but output is coming as 1 i dont know why..</p> <pre><code>class A{ public: int a .... .... </code></pre> <p>OUTPUT:</p> <p>A's construction done</p> <p>B's Construction Done</p> <p>A's fun</p> <p>0027F91C</p> <p>1 (why 1) and no errors as I was able to get when I tried to access protected member?</p>
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    1. USSam Miller
    1. USAstro - Amit
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    1. CO@Sergey sorry typing mistake
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      1. USAstro - Amit
 

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