using System;

// 1. Create an interface IShape

​

public interface IShape

{

// 1.1 [Code] Declare one property Name (string)

    string Name { get; set; }

// 1.2 [Code] Declare one function CalculateArea()

//     Input: none

//     Output: double

    double CalculateArea();

}

​

​

// 2. Create an interface IColor

​

public interface IColor

{

// 2.1 [Code] Declare one property Color (string)

    string Color { get; set; }

// 2.2 [Code] Declare one function IsYellow()

//     Input: none

//     Output: bool

    bool IsYellow();

}

​

//3. Create a class inherit from IShape and IColor

public class Triangle : IShape, IColor //[Code] 3.1 Inherit from both Ishape and IColor

{

    // [Code] 3.2 Create a private field and a public property for Name variable.

    //        The length of name should be more than 0. If length is zero,

    //        issue a warning and do not change the current value.

    //        (Hint: use Length property of a string.)

    private string _name;

    public string Name

    {

        get { return _name; }

        set 

        {

            if (value.Length > 0) _name = value;

            else Console.WriteLine("Warning: Name cannot be empty.");

        }

    }

    // [Code] 3.3 Create a protected property for Color variable.

    //        Access modifier is "protected"

    //

    // Hint: protected vs private

    // A protected member is accessible within its class and by derived class instances.

    // Private members are accessible only within the body of the class or 

    // the struct in which they are declared/

    public string Color { get; set; }

    // [Code] 3.4 Create two properties: Base (double) and Height (double)

    //        Use auto-implementation

    public double Base { get; set; }

    public double Height {get; set; }

    // Default constructor

    public Triangle() { }

​

    // [Code] 3.4 Declare the second constructor with four parameters to set values for Name, Base, and Height, and Color

    public Triangle(string name, double b, double height, string color)

    {

        Name = name;

        Base = b;

        Height = height;

        Color = color;

    } 

    // [Code] 3.5 Implement CalculateArea function

    //        Input: none

    //        Output: double

    //        Rule: Please use the formula to calculate the area for a triangle. (hint: use Base and Height).

    public double CalculateArea()

    {

        return Base * Height / 2;

    }

    // [Code] 3.6 Implement IsYellow function

    //        Input: none

    //        Output: bool

    //        Rule: if the color is yellow, return true; false, otherwise.

    //              The color string should be case insensitive

    public bool IsYellow()

    {

        return Color.ToLower() == "yellow";

    }

} 

​

public class Program

{

    public static void Main()

    {

        // [Code] 1. Create a triangle object

        // Input: "Triangle", 8.5, 4.2, "blue" (use one line)

        Triangle t = new Triangle("Triangle", 8.5, 4.2, "blue");

        Triangle t2 = new Triangle();

        t2.Base = 8.5;

        t2.Height = 4.2;

        t2.Color = "blue";

        t2.Name = "Triangle"; 

        // [Question] What is the value of the area for the created triangle?

        // (Use Console.WriteLine and CalculateArea function to find the answer)

        // Ans: 

        Console.WriteLine("Area=" + t.CalculateArea());

        // [Question] Is the triangle object's color yellow?

        // (Use Console.WriteLine and IsYellow function to find the answer)

        // Ans: 

        Console.WriteLine("Yellow?=" + t.IsYellow());

    }

}