Pro - 5

Develop a program to illustrate a copy constructor so that a string may be duplicated into another variable either by assignment or copying. 

// filename: Main.java   class Complex {       private double re, im;           // A normal parametrized constructor     public Complex(double re, double im) {         this.re = re;         this.im = im;     }           // copy constructor     Complex(Complex c) {         System.out.println("Copy constructor called");         re = c.re;         im = c.im;     }            // Overriding the toString of Object class     @Override     public String toString() {         return "(" + re + " + " + im + "i)";     } }   public class Main {       public static void main(String[] args) {         Complex c1 = new Complex(10, 15);                   // Following involves a copy constructor call         Complex c2 = new Complex(c1);             // Note that following doesn't involve a copy constructor call as         // non-primitive variables are just references.         Complex c3 = c2;             System.out.println(c2); // toString() of c2 is called here     } }

Output:

Copy constructor called
(10.0 + 15.0i)

Now try the following Java program:

// filename: Main.java   class Complex {       private double re, im;       public Complex(double re, double im) {         this.re = re;         this.im = im;     } }   public class Main {           public static void main(String[] args) {         Complex c1 = new Complex(10, 15);          Complex c2 = new Complex(c1);  // compiler error here     } }