using System;

​

    public class Invoice {

     String partNumber;

     String partDescription;

     int quantity;

     double price;

    public Invoice(String pNum, String pDesc, int qty, double prc) {

        if ((pNum != null)) {

            this.partNumber = pNum;

        }

        else {

            this.partNumber = null;

        }

        if ((pDesc != null)) {

            this.partDescription = pDesc;

        }

        else {

            this.partDescription = null;

        }

        if ((qty > 0)) {

            this.quantity = qty;

        }

        else {

            this.quantity = 0;

        }

        if ((prc > 0)) {

            this.price = prc;

        }

        else {

            this.price = 0;

        }

    }

    public String getPartNum() {

        return this.partNumber;

    }

    public String getPartDesc() {

        return this.partDescription;

    }

    public int getQuantity() {

        return this.quantity;

    }

    public double getPrice() {

        return this.price;

    }

    public void setPartNum(String pNum) {

        if ((pNum != null)) {

            this.partNumber = pNum;

        }

        else {

            this.partNumber = null;

        }

    }

    public void setPartDesc(String pDesc) {

        if ((pDesc != null)) {

            this.partDescription = pDesc;

        }

        else {

            this.partDescription = null;

        }

    }

    public void setQuantity(int qty) {

        if ((qty > 0)) {

            this.quantity = qty;

        }

        else {

            this.quantity = 0;

        }

    }

    public void setPrice(double prc) {

        if ((prc > 0)) {

            this.price = prc;

        }

        else {

            this.price = 0;

        }

    }

    public double getInvoiceAmount() {

        return (((double)(this.quantity)) * this.price);

    }

}

public class InvoiceTest {

    public static void Main() {

       Invoice inv = new Invoice("P1", "Widget", 10, 20.5);

       double cost = inv.getInvoiceAmount();

       Console.WriteLine("Part {0}; Desc {1}; Quantity {2}; Price Each {3:C}; Total Cost {4:C}",inv.getPartNum(), inv.getPartDesc(), inv.getQuantity(), inv.getPrice(), cost);

       Invoice inv2 = new Invoice("P2", "Widget Holder", 2, -1.25);

       double cost2 = inv2.getInvoiceAmount();

       Console.WriteLine("Part {0}; Desc {1}; Quantity {2}; Price Each {3:C}; Total Cost {4:C}", inv2.getPartNum(), inv2.getPartDesc(), inv2.getQuantity(), inv2.getPrice(), cost2);

       Console.WriteLine();

    }

}

​

​