Ivor Horton's Beginning Visual C++ 2012

ARRAYS OF OBJECTS

You can create an array of objects in exactly the same way as you created an ordinary array of elements of a fundamental type. Each element of an array of objects that you don’t initialize causes the default constructor to be called.

TRY IT OUT: Arrays of Class Objects

The definition of CBox in this example includes a specific default constructor:

// Ex7_11.cpp
// Using an array of class objects
#include <iostream>
using std::cout;
using std::endl;
 
class CBox                             // Class definition at global scope
{
  public:
    // Constructor definition
    explicit CBox(double lv, double bv = 1.0, double hv = 1.0)
    {
 
      cout << endl << "Constructor called.";
      m_Length = lv;                   // Set values of
      m_Width = bv;                    // data members
      m_Height = hv;
    }
 
    CBox()                             // Default constructor
    {
      cout << endl
           << "Default constructor called.";
      m_Length = m_Width = m_Height = 1.0;
    }
 
    // Function to calculate the volume of a box
    double Volume() const
    {
      return m_Length*m_Width*m_Height;
    }
 
  private:
    double m_Length;                   // Length of a box in inches
    double m_Width;                    // Width of a box in inches
    double m_Height;                   // Height of a box in inches
 
};
 
int main()
{
  CBox boxes[5];                       // Array of CBox objects declared
  CBox cigar(8.0, 5.0, 1.0);           // Declare cigar box
 
  cout << endl
       << "Volume of boxes[3] = " << boxes[3].Volume()
       << endl
       << "Volume of cigar = " << cigar.Volume();
 
  cout << endl;
  return 0;
}

The program produces this output:

Default constructor called. Default constructor called. Default constructor called. Default constructor called. ...