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References to Base class

Anmol444 (638)
box.h

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// Box.h in Ex9_09
#pragma once
#include <iostream>

class CBox                             // Base class
{
  public:
    // Function to show the volume of an object
    void ShowVolume() const
    {
      std::cout << std::endl << "CBox usable volume is " << Volume(); 
    }

    // Function to calculate the volume of a CBox object
    virtual double Volume() const
    { return m_Length*m_Width*m_Height; }

    // Constructor
    explicit CBox(double lv = 1.0, double wv = 1.0, double hv = 1.0) : m_Length(lv), m_Width(wv), m_Height(hv) {}

  protected:
    double m_Length;
    double m_Width;
    double m_Height;
};


CGlassBox.h

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// GlassBox.h in Ex9_09
#pragma once
#include "Box.h"

class CGlassBox: public CBox           // Derived class
{
  public:
    // Function to calculate volume of a CGlassBox
    // allowing 15% for packing
    virtual double Volume() const override
    { return 0.85*m_Length*m_Width*m_Height; }

	double add(int x,int a)
	{return x+a;
	}
    // Constructor
    CGlassBox(double lv, double wv, double hv): CBox(lv, wv, hv){}
};



Main

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// Ex9_09.cpp
// Using a reference to call a virtual function
#include <iostream>
#include "GlassBox.h"                  // For CBox and CGlassBox
using std::cout;
using std::endl;

void Output(const CBox& aBox);         // Prototype of function

int main()
{
  CBox myBox(2.0, 3.0, 4.0);           // Declare a base box
  CGlassBox myGlassBox(2.0, 3.0, 4.0); 
  CBox& nib=myBox;
  CBox& ni=myGlassBox;// Declare derived box of same size

  Output(nib);                       // Output volume of base class object
  Output(ni);                  // Output volume of derived class object

  cout<<ni.ShowVolume()<<endl;
  return 0;
}

void Output(const CBox& aBox)
{
  aBox.ShowVolume();
}



On line 20 I know it should give a error but on my compiler I think it is not giving the correct error?

1>------ Build started: Project: Tests, Configuration: Debug Win32 ------
1>  Ex9_09.cpp
1>c:\users\anmol\documents\visual studio 2012\projects\c++ book\code from book\chapter 09\ex9_09\ex9_09.cpp(20): error C2679: binary '<<' : no operator found which takes a right-hand operand of type 'void' (or there is no acceptable conversion)
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========


There was way more output but I couldn't fit it all here.

This is the error it should be giving

1>------ Build started: Project: Tests, Configuration: Debug Win32 ------
1>  Ex9_09.cpp
1>c:\users\anmol\documents\visual studio 2012\projects\c++ book\code from book\chapter 09\ex9_09\ex9_09.cpp(20): error C2039: 'add' : is not a member of 'CBox'
1>          c:\users\anmol\documents\visual studio 2012\projects\c++ book\code from book\chapter 09\ex9_09\box.h(6) : see declaration of 'CBox'
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========


Instead of using that function I used the add one in CGlassBox and I got expected behavior.


Edit: I figured it out, it is because it returns void right? and you cant output void lol
Last edited on
MiiNiPaa (8886)
You should replace line 20 with just ni.ShowVolume()
Anmol444 (638)
I know I figured it out xD
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