### Example of Explicit Initialization by Constructor

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The following example shows the declaration and use of several constructors that explicitly initialize class objects:

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    // This example illustrates explicit initialization
    // by constructor.

    #include <iostream.h>
    class complx
    {
          double re, im ;
    public:
          complx();   // default constructor
          complx(const complx& c) {re = c.re; im = c.im;}
                      // copy constructor
          complx( double r, double i = 0.0) {re = r; im = i;}
                      // constructor with default trailing argument
          void display()
          {
                cout << "re = "<< re << " im = " << im << endl;
          }
    };

    void main ()
    {
          complx one(1);      // initialize with complx(double, double)
          complx two = one;   // initialize with a copy of one
                              // using complx::complx(const complx&)
          complx three = complx(3,4);  // construct complx(3,4)
                                       // directly into three
          complx four;                 // initialize with default constructor
          complx five = 5;             // complx(double, double) & construct
                                       // directly into five
          one.display();
          two.display();
          three.display();
          four.display();
          five.display();
    }

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    *

The above example produces the following output:

    re = 1 im = 0
    re = 1 im = 0
    re = 3 im = 4
    re = 0 im = 0
    re = 5 im = 0

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