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2.4 Constructor chaining

  1. Change the code of the constructor with signature Circle(double radius) as follows:

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    public Circle(double radius) : this(radius, 0, 0, "white")
{
}

    Note that this(radius, 0, 0, "white") calls the all-args constructor within the class. The default values for centerX, centerY, and color are passed.

  2. Change the code of the default constructor Circle() as follows:

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    public Circle() : this(1)
{
}
    • this(1) now refers to the constructor with signature Circle(double radius) within the class. The default value for radius is passed.
    • The most generic constructor (the default constructor) calls the more specific constructor, which in turn calls the most specific constructor (the all-args constructor).
    • Note that every default value is determined in only one place.

  3. Modify the code in the Main method as follows: 

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    Circle myAllArgsCircle = new Circle(3, 1, 4, "green");
Console.WriteLine(myAllArgsCircle.CalculatePerimeter());
Console.WriteLine(myAllArgsCircle.CalculateArea());

Circle myDefaultCircle = new Circle();
Console.WriteLine(myDefaultCircle.CalculatePerimeter());
Console.WriteLine(myDefaultCircle.CalculateArea());

Circle myRadiusCircle = new Circle(6);
Console.WriteLine(myRadiusCircle.CalculatePerimeter());
Console.WriteLine(myRadiusCircle.CalculateArea());

  4. Run your program. Your output will look like this: 

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    18.84955592153876
28.274333882308138
6.283185307179586
3.141592653589793
37.69911184307752
113.09733552923255

    Note that the output is the same as in Exercise 1.3.

  5. Try some other values and view the output.