calculate the sum of ListNodes

Question

0.00/5 (No votes)

See more:

I want to calculate the sum of ListNodes, but it says that "'s' Specified cast is not valid."

C#

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

namespace ConsoleApplication1
{
    class Program
    {
        
        static void Main(string[] args)
        {
            List listOfNodes = new List();
           
            Random r = new Random();
            int sum = 0;
            for (int i = 0; i < 10; i++)
            {
                listOfNodes.addObjects(r.Next(1, 100));
               
            }
            listOfNodes.DisplayList();
            foreach (object s in listOfNodes) 
               sum += (int)s;
            Console.WriteLine(sum);

            Console.ReadLine();
            
        }

        class ListNode
        {
            public object inData { get; private set; }
            public ListNode Next { get; set; }

            public ListNode(object dataValues)
                : this(dataValues, null) { }

            public ListNode(object dataValues, 
                ListNode nextNode)
            {
                inData = dataValues; Next = nextNode;
            }
        } // class ListNode-s dasasruli

        public class List : IEnumerable
        {
            private ListNode firstNode, lastNode;
            private string name;

            public List(string nameOfList)
            {
                name = nameOfList;
                firstNode = lastNode = null;
            }

            public List()
                : this("listOfNodes") { }
           
           
            public void addObjects(object inItem)
            {
                if (isEmpty())
                { firstNode = lastNode = new ListNode(inItem); }
                else { firstNode = new ListNode(inItem, firstNode); }
            }
            
            private bool isEmpty()
            {
                return firstNode == null;
            }

            public void DisplayList()
            {
                if (isEmpty())
                { Console.Write("Empty " + name); }
                else
                { 
                    Console.Write("The " + name + " is:\n");

                    ListNode current = firstNode;

                    while (current != null)
                    {
                        Console.Write(current.inData + " ");
                        current = current.Next;
                    }
                    Console.WriteLine("\n");
                }
            }

            public IEnumerator GetEnumerator()
            {
                ListNode node = firstNode;
                while (node != null)
                {
                    yield return node;
                    node = node.Next;
                }
            }
        }//end of class List
    }
}

Posted 27-Nov-13 3:06am

Temur Mukbaniani

Add a Solution

Comments

♥…ЯҠ…♥ 27-Nov-13 9:07am

In which line?

2 solutions

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

OriginalGriff · Answer 1 · 2013-11-27T03:17:00

You can't cast a ListNode to an integer - that's just silly!

C#

foreach (object s in listOfNodes)
    sum += (int)s;

s is a ListNode - because that is what your GetEnumerator method returns:

C#

public IEnumerator GetEnumerator()
{
    ListNode node = firstNode;
    while (node != null)
    {
        yield return node;
        node = node.Next;
    }
}

Probably, what you actually want to do is change the GetEnumerator to return the value instead:

C#

public IEnumerator GetEnumerator()
    {
    ListNode node = firstNode;
    while (node != null)
        {
        yield return node.inData;
        node = node.Next;
        }
    }

Matt T Heffron · Answer 2 · 2013-11-27T06:37:00

OriginalGriff suggested changing what the enumerator returned.
I'd argue against that because it is not the expected semantics of GetEnumerator().
I'd use object less and correct types more:

C#

public class List : IEnumerable<ListNode> ...

and

C#

public IEnumerator<ListNode> GetEnumerator() ...

then the summation can be:

C#

foreach (ListNode s in listOfNodes)
  sum += (int)s.inData;

or, using Linq:

C#

sum = listOfNodes.Sum(s => (int)s.inData);

And, of course, if ListNode.inData will always be int,
then declare it as such and the cast to int is unnecessary.

calculate the sum of ListNodes

2 solutions

Solution 1

Solution 2

Add your solution here

Preview 0