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POC++ Printing Data on a STL list
 

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  1. POC++ Printing Data on a STL list
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    <p>I have a Base class, and a Derived class; on the other hand I made a List class that uses the STL . Base class has a virtual function called <code>PrintData()</code>, that prints an integer that belongs to the Base class. In the Derived class; the same function <code>printData()</code> prints an integer that belong to the Derived and the other one from the Base class.</p> <p>The thing is that, in the class List, I'm just getting the data from Base, no matter if I inserted a Derived instance on the list.</p> <p>I need to print Derived data, that is supposed to have Base data as well. Here is the code:</p> <pre><code> #pragma once; #include &lt;iostream&gt; #include &lt;sstream&gt; using namespace std; class Base{ protected: int x; public: Base(){ x=3; } void setX(int a){ x=a; } int getX(){ return x; } virtual string printData(){ stringstream f; f&lt;&lt;getX()&lt;&lt;endl; return f.str(); } }; class Derived : public Base{ int a; public: Derived(){ this-&gt;Base::Base(); a=4; } void setA(int x){ a=x; } int getA(){ return a; } string printData(){ stringstream a; a&lt;&lt;getA()&lt;&lt;getX()&lt;&lt;endl; return a.str(); } }; </code></pre> <p>And here is the List class:</p> <pre><code> #pragma once; #include "Prueba.cpp" #include &lt;list&gt; class Lista{ list&lt;Base*&gt; lp; public: Lista(){ } void pushFront(Base* c){ lp.push_front(c); } void pushBack(Base* c){ lp.push_back(c); } void printList(){ list&lt;Base*&gt;::const_iterator itr; for(itr=lp.begin(); itr!=lp.end(); itr++){ cout&lt;&lt;(*itr)-&gt;printData(); } } ~Lista(){ } }; int main(){ Derived* d=new Derived(); Lista* l=new Lista(); l-&gt;pushFront(d); l-&gt;printList(); system("Pause"); return 0; } </code></pre> <p>I'm just getting the Base class data, that is an integer with the value of 3. But I'm not getting the integer from Derived that has the value of 4.</p>
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    1. USJohn Dibling
    1. USJosé Del Valle
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    1. COIt's never necessary to call `Base::Base`, the compiler does this for you automatically. The base class constructor always comes before the derived class constructor.
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      1. USMark Ransom
    2. COThis seems to work when I try it. Are you sure you're compiling and running the right thing?
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      1. USNate Kohl
 

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