显示从文本框到列表框的输出，C＃

Question

So I'm creating a LinkedList in C# winforms, and now I want to display the list visually when adding, removing and searching for node values. I use 3 button controls, one for adding nodes, removing nodes and the last for searching for a nodes value. Then, I have a textbox that should read in a int value from user (ex. 10), and then display that value as a linked list, in a Listbox. So, Ive created a Node class and a linkedlist class. The Node class holds a value and a reference to the next node:

class Node
{
    public int value;
    public Node next;

    public int Value
    {
        get { return this.value; }
        set { this.value = value; } 
    }

    public Node Next
    {
        get;
        set;
    }

    public Node()
    {
        this.Next = null;
        this.value = 0;
    }
}

and a LinkedList class with all my methods (I will only write my add method, so It wont be too much code)

public void Add(int val)
    {
       Node newNode = new Node();
       newNode.value = val;

       if (head == null)
           head = newNode;

       if (current.Next == null)
       {
           current.Next = newNode;
           current = newNode;
       }
       size++;
   }

So, Now what imm trying to Do is to write some code so that when I input a int number in the textbox, it should appear in the Listbox as a LinkedList (with my add method from my LinkedList class)

I tried to do this on the event handler for my Add button:

LinkedList l1 = new LinkedList();
l1.Add(textBox1);

But clearly that is not even logical. Could someone please point me to the right direction here?

Answer 1

You probably want

l1.Add(Int32.Parse(textBox1.Text))

textBox1 is an object representing the textbox, not the value stored in it (which is the Text property). TextBox s store their value in string format, hence the use of Int32.Parse() (which converts from string (or other values) to int.

It should be noted that Int32.Parse is not the safest way to do this, and if you want to verify that the value is truly an int you should use Int32.TryParse()

Answer 2

If your ListBox is called listBox1 you add to it like this:

listBox1.Items.Add(something);

You can add strings directly but you probably want to add one of your LinkedList objects. You can add it also like above..

listBox1.Items.Add(l1 );

..but it won't show anything useful until you add a ToString method to your LinkedList class:

public override string ToString()
{
    return "value : " + this.value; // maybe you want to display more here?
}

It is up to you to decide what you want displayed hee; maybe indicators if the links are set..? I also suggest adding one or more constructors to your LinkedList class to set at least the value right away:

public Node(int value_)
{
    this.Next = null;
    this.value = value_;
}

Then your above code could turn to:

LinkedList l1 = new LinkedList(textBox1.Text);
listView1.Items.Add(l1);