using System;

public class Invoice {

    string part_number;                 //declaring instance variables of the Invoice class.

    string part_description;

    int item_quantity;

    double item_price;

    public Invoice(string part_number, string part_description, int item_quantity, double item_price) {     //constructor

        part_num = part_number;

        part_desc = part_description;

        item_quant = item_quantity;

        price = item_price;

    }

    public string part_num {                    //properties for the instance variables.

        get {return part_number;}

        set {part_number = value;}

    }

    public string part_desc {

        get {return part_description;}

        set {part_description = value;}

    }

    public int item_quant {

        get {return item_quantity;}

        set {

            if(value<0) value = 0;

            item_quantity = value;          //quantity and price remain unchanged if their respective values are negative.

        }

    }

    public double price {

        get {return item_price;}

        set {

            if(value<0) value = 0;

            price = value;

        }

    }

    public double GetInvoiceAmount() {      //method that calculates the invoice amount

        return item_quantity * item_price;

    }

}

​

public class Program

{

    public static void Main()

    {

        Invoice I = new Invoice("14A6B", "Samsung Refrigerator", 3, 499);   //(number, description, quantity, price)

        double I_Amount = I.GetInvoiceAmount();     //I_Amount now containts 3*499

        Console.WriteLine("Part:     ", I.part_num);

        Console.WriteLine("Description:     ", I.part_desc);

        Console.WriteLine("Quantity:     ", I.item_quant);

        Console.WriteLine("Price per item:     ", I.price);

        Console.WriteLine("Total Invoice Cost:     ", I_Amount);

    }

}