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POVectors of variables vs vector of pointers
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  1. POVectors of variables vs vector of pointers
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    copied!<p>I was just curious about the differences of using vectors of variables vs a vector of pointers with dynamic memory, and I've found something that confused me. I have a simple main.cpp that looks like this,</p> <pre><code>#include &lt;iostream&gt; #include &lt;vector&gt; using namespace std; class A { public: A() { x = 2;} virtual ~A() { cout &lt;&lt; "I'm a dead A\n";} public: int x; }; class B : public A { public: B() {x = 4;} ~B() { cout &lt;&lt; "I'm a dead B\n";} }; class C : public A { public: C() { x = 6;} ~C() { cout &lt;&lt; "I'm a dead C\n";} }; int main() { cout &lt;&lt; "Starting variable list\n"; std::vector&lt;A&gt; list; list.push_back( B() ); list.push_back( A() ); list.push_back( B() ); list.push_back( C() ); list.push_back( A() ); for(std::vector&lt;A&gt;::iterator it = list.begin(); it != list.end(); it++) { cout &lt;&lt; it-&gt;x &lt;&lt; endl; } cout &lt;&lt; "\n\nStarting pointer list\n"; std::vector&lt;A *&gt; ptrList; ptrList.push_back( new B()); ptrList.push_back( new A()); ptrList.push_back( new B()); ptrList.push_back( new C()); ptrList.push_back( new A()); for(std::vector&lt;A *&gt;::iterator it = ptrList.begin(); it != ptrList.end(); it++) { cout &lt;&lt; (*it)-&gt;x &lt;&lt; endl; } for(std::vector&lt;A *&gt;::iterator it = ptrList.begin(); it != ptrList.end(); it++) { delete *it; } system("PAUSE"); return 0; } </code></pre> <p>And I get a printout that looks like this:</p> <pre><code>Starting variable list I'm a dead B I'm a dead A I'm a dead A I'm a dead A I'm a dead A I'm a dead A I'm a dead B I'm a dead A I'm a dead A I'm a dead A I'm a dead A I'm a dead C I'm a dead A I'm a dead A I'm a dead A I'm a dead A I'm a dead A I'm a dead A 4 2 4 6 2 Starting pointer list 4 2 4 6 2 I'm a dead B I'm a dead A I'm a dead A I'm a dead B I'm a dead A I'm a dead C I'm a dead A I'm a dead A Press any key to continue . . . </code></pre> <p>What and why did all those destructions occurr in the normal variable list?</p>
 

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