Chapter 6 Exercise 4

narukami · December 29th, 2011, 01:53 AM

Hi all, I'm trying to work out a solution for exercise 4, but I think I'm making some very elementary mistakes. The answer in the back of the book is much shorter, but I'd like to understand what I'm doing wrong here if possible.

This is my code:

Code:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args);
        
     struct order
     {
         public string itemName;
         public int unitCount;
         public double unitCost;
         public double totalCost() {return unitCost * unitCount;}
     }
    }
    Console.WriteLine("This function calculates the total cost of all units.");
    itemName myItem;
    Console.WriteLine("Please enter the name of the item you would like to purchase.");
    myItem = console.ReadLine();
    Console.WriteLine("Thank you. Now please enter the number of items you would like to purchase.");
    unitCount myCount;
    myCount = Console.ReadLine();
    Console.WriteLine("Thank you. Now please enter the cost of a {0}.", myItem);
    unitCost = myCost;
    myCost = Console.ReadLine();
    totalCost = myTotal;
    Console.WriteLine("Thank you! The total cost of your {0} orders of item {1} is {2}.", myCount, myItem, myTotal);
    Console.ReadKey();
     
}

This is the error message I'm getting:

A namespace cannot directly contain members such as fields or methods (line 20)

Thanks for all your help! :)

arun_babu_a · December 29th, 2011, 04:08 AM

I made some changes to your source code and that works fine for me
please check the code below

Code:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ConsoleApplication1
{
    class Program
    {
        struct Order
        {
            public string itemName;
            public int unitCount;
            public double unitCost;
            public double totalCost()
            { return unitCost * unitCount;
            }
        }
        static void Main(string[] args)
        {
      
            Order myOrder;
            Console.WriteLine("Please enter the name of the item you would like to purchase.");
            myOrder.itemName = Console.ReadLine();
            Console.WriteLine("Thank you. Now please enter the number of items you would like to purchase.");
            myOrder.unitCount = Convert.ToInt32(Console.ReadLine());
            Console.WriteLine("Thank you. Now please enter the cost of a {0}.", myOrder.itemName);
            myOrder.unitCost =Convert.ToDouble(Console.ReadLine());
            Console.WriteLine("Thank you! The total cost of your {0} orders of item {1} is {2}.", myOrder.unitCount, myOrder.itemName,myOrder.totalCost());
            Console.ReadKey();

        }
    }
}

In your code u defined itemName myItem;, am also confused on this,Is it possible to declare a variable like this?

You defined the struct in main function,Its better to place outside the main.

Also without declaring a struct variable is it possible to access its members?

syntax for calling a function is not like this in your code

please don't mark this as answer because I am also a beginner like you so someone else also verify this one.

narukami · December 30th, 2011, 04:02 PM

Thanks for your reply! That code does work. However, just moving the Main line doesn't fix my code, so I'm going to have to look this up a bit more...

This method of declaring variables is used a few times in the book, such as the Try It Out on page 47, for instance. It just splits the declaration and the definition in two lines, like this:
int myInt;
myInt = 5;

as opposed to writing myInt = 5;

So your code is also more efficient, since it's nice and short! :)