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POderived class's virtual assignment operator not being called
 

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  1. POderived class's virtual assignment operator not being called
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    <p>I'm pretty new to C++, and am trying to come to grips with virtual assignment. The program below consists of an abstract base class with two data members, and a derived class with one. When I set an abstract pointer to a derived object, the program uses the abstract version of operator= rather than the derived version, even though they're both declared "virtual." What am I doing wrong here?</p> <p>Thanks in advance,</p> <p>Jay</p> <pre><code>#include &lt;iostream&gt; #include &lt;cstring&gt; class Abstract { protected: char * label; int rating; public: Abstract(const char * l = "null", int r = 0); virtual Abstract &amp; operator=(const Abstract &amp; rs); virtual ~Abstract() { delete [] label; } virtual void view() const = 0; }; class Derived : public Abstract { private: char * style; public: Derived(const char * s = "none", const char * l = "null", int r = 0); ~Derived() { delete [] style; } virtual Derived &amp; operator=(const Derived &amp; rs); virtual void view() const; }; Abstract::Abstract(const char * l , int r ) { label = new char[std::strlen(l) + 1]; std::strcpy(label, l); rating = r; } Abstract &amp; Abstract::operator=(const Abstract &amp; rs) { if (this == &amp;rs) return *this; delete [] label; label = new char[std::strlen(rs.label) + 1]; std::strcpy(label, rs.label); rating = rs.rating; return *this; } Derived::Derived(const char * s, const char * l, int r) : Abstract(l, r) { style = new char[std::strlen(s) + 1]; std::strcpy(style, s); } Derived &amp; Derived::operator=(const Derived &amp; hs) { if (this == &amp;hs) return *this; Abstract::operator=(hs); style = new char[std::strlen(hs.style) + 1]; std::strcpy(style, hs.style); return *this; } void Derived::view() const { std::cout &lt;&lt; "label: " &lt;&lt; label &lt;&lt; "\nrating: " &lt;&lt; rating &lt;&lt; "\nstyle: " &lt;&lt; style; } int main () { using namespace std; char label[20], style[20]; int rating; cout &lt;&lt; "label? "; cin &gt;&gt; label; cout &lt;&lt; "rating? "; cin &gt;&gt; rating; cout &lt;&lt;"style? "; cin &gt;&gt; style; Derived a; Abstract * ptr = &amp;a; Derived b(style, label, rating); *ptr = b; ptr-&gt;view(); return 0; } </code></pre>
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    1. COUnrelated, but why are you using `char*`s?
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    2. COWithout going into details, you're doing it wrong. Read http://www.learncpp.com/cpp-tutorial/123-virtual-destructors-virtual-assignment-and-overriding-virtualization/ , and search google for "virtual assignment operator". This has been discussed a lot already.
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    3. COTo keep the code shorter, I tried to remove things that were extraneous to my question, including dynamic memory (hence the char *s)
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