How to display LinkedList in MessageBox

Question

3.00/5 (2 votes)

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Trying to print LinkedList with MessageBox. Typically I use this method to display arrays.

C#

private void DisplayList<T>(LinkedList<T> list)
        {
            string strDisplay = string.Join(Environment.NewLine, list);
            MessageBox.Show(strDisplay);
        }

However in this instance I want to reverse the order of LinkedList before displaying. The below doesn't compile. Error is that last strDisplay is unassigned. Any suggestions how best to do this?

XML

private void displayListReversed<T>(LinkedList<T> list)
        {
            LinkedListNode<T> currentNode = list.Last;
            string strDisplay;
            while (currentNode != null)
            {
                strDisplay = strDisplay + Environment.NewLine + currentNode.Value;
                currentNode = currentNode.Previous; // go backwards through nodes
            }

            MessageBox.Show(strDisplay); // doesn't work
        }

Posted 29-Sep-14 10:09am

needyt

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[no name] 29-Sep-14 16:15pm

string strDisplay = string.Empty;

needyt 29-Sep-14 16:19pm

Thanks for quick reply. Worked like a charm.

I have one more question if you'll bear with me... why did initializing it as empty work? Whats the difference?

Sergey Alexandrovich Kryukov 29-Sep-14 16:30pm

There is no "difference". There is no default initialization for variables, not allowed by syntax (but type members are all initialized, say, with null).
—SA

[no name] 29-Sep-14 19:22pm

The difference is that string strDisplay; initializes your string to nothing and string strDisplay = string.Empty; initializes the string to an empty string which is something and not nothing.

BillWoodruff 29-Sep-14 19:15pm

CodeProject is your friend:

http://www.codeproject.com/Articles/27742/How-To-Reverse-a-Linked-List-Different-Ways

Maciej Los 1-Oct-14 17:36pm

Instead of string variable, use StringBuilder class.

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TheRealSteveJudge · Answer 1 · 2014-11-14T01:18:00

Hi,

I would like to suggest a more elegant implementation.

C#

using System;
using System.Collections.Generic;
using System.Linq;
using System.Windows;

namespace LinkedListTest
{
    public partial class MainWindow : Window
    {
        LinkedList<int> linkedList;

        public MainWindow()
        {
            this.Loaded += MainWindow_Loaded;

            InitializeComponent();
        }

        void MainWindow_Loaded(object sender, RoutedEventArgs e)
        {
            linkedList = new LinkedList<int>();

            for(int i=0; i<10; i++)
            {
                linkedList.AddLast(i);
            }

            DisplayList(linkedList);
            DisplayListReversed(linkedList);
        }

        private void DisplayList<T>(LinkedList<T> list)
        {
            string strDisplay = string.Join(Environment.NewLine, list);
            MessageBox.Show(strDisplay);
        }

        private void DisplayListReversed(LinkedList<int> linkedList)
        {
            linkedList = new LinkedList<int>(linkedList.Reverse());
            DisplayList(linkedList);
        }
    }
}

Happy coding,

Stephan