C# Discussion Boards - CodeProject

Re: The best overload method match system.IComparable has invalid arguments

29-Apr-08 2:15

when i am trying to insert i the patient detail in the BINARY SEARCH TREE it give me the following error "The best overload method for IBSTree.Insert(System.Icomparable) has some invalid arguments".

<br />
//This is the interface<br />
using System;<br />
using System.Collections;<br />
<br />
<br />
    //Invariants: FirstName, LastName,StreetName and suburb sre strings of chars and<br />
    //            their length > 0 and street no > 0 and age > 0<br />
<br />
    public interface IPatient<br />
    {<br />
        //Pre: true<br />
        //Post: return the first name of the patient <br />
        string FirstName { get; set; }<br />
<br />
        //Pre: true<br />
        //Post: return the last name of the patient <br />
        //string LastName { get; set; }<br />
<br />
    }<br />
<br />
<br />
//here is the IPatient implementation<br />
using System;<br />
using System.Collections;<br />
<br />
<br />
<br />
    public class Patient: IPatient<br />
    {<br />
        private string fname;<br />
                <br />
        public string FirstName<br />
        {<br />
            get<br />
            {<br />
                return fname;<br />
            }<br />
            set<br />
            {<br />
                fname = value;<br />
            }<br />
        }<br />
        public int CompareTo(IPatient obj)<br />
        {<br />
            Patient p1 = (Patient)obj; <br />
            return fname.CompareTo(p1.fname);<br />
        } <br />
  }<br />
<br />
//trying to store the details of the patient in Binary Search Tree<br />
using System;<br />
using System.Collections;<br />
<br />
    public class BTreeNode<br />
    {<br />
        private IComparable item; // value<br />
        private BTreeNode lchild; // reference to its left child <br />
        private BTreeNode rchild; // reference to its right child<br />
<br />
        public BTreeNode(IComparable item)<br />
        {<br />
            this.item = item;<br />
            lchild = null;<br />
            rchild = null;<br />
        }<br />
<br />
        public IComparable Item<br />
        {<br />
            get { return item; }<br />
            set { item = value; }<br />
        }<br />
<br />
        public BTreeNode LChild<br />
        {<br />
            get { return lchild; }<br />
            set { lchild = value; }<br />
        }<br />
<br />
        public BTreeNode RChild<br />
        {<br />
            get { return rchild; }<br />
            set { rchild = value; }<br />
        }<br />
    }<br />
<br />
<br />
    public class BSTree : IBSTree<br />
    {<br />
        private BTreeNode root;<br />
        public BSTree()<br />
        {<br />
            root = null;<br />
        }<br />
<br />
        public bool IsEmpty()<br />
        {<br />
            return root == null;<br />
        }<br />
<br />
        public bool Search(IComparable item)<br />
        {<br />
            return Search(item, root);<br />
        }<br />
<br />
        private bool Search(IComparable item, BTreeNode r)<br />
        {<br />
            if (r != null)<br />
            {<br />
                if (item.CompareTo(r.Item) == 0)<br />
                    return true;<br />
                else<br />
                    if (item.CompareTo(r.Item) < 0)<br />
                        return Search(item, r.LChild);<br />
                    else<br />
                        return Search(item, r.RChild);<br />
            }<br />
            else<br />
                return false;<br />
        }<br />
<br />
<br />
        // pre: item != null, it might be incomplete, but must contain the key<br />
        // post: return item if item is in the binary search tree;<br />
        //	     otherwise, return null.<br />
        public IComparable PartialSearch(IComparable item)<br />
        {<br />
            return PartialSearch(item, root);<br />
        }<br />
<br />
        private IComparable PartialSearch(IComparable item, BTreeNode r)<br />
        {<br />
            if (r != null)<br />
            {<br />
                if (item.CompareTo(r.Item) == 0)<br />
                    return r.Item;<br />
                else<br />
                    if (item.CompareTo(r.Item) < 0)<br />
                        return PartialSearch(item, r.LChild);<br />
                    else<br />
                        return PartialSearch(item, r.RChild);<br />
            }<br />
            else<br />
                return null;<br />
        }<br />
<br />
<br />
        public void Insert(IComparable item)<br />
        {<br />
            if (root == null)<br />
            {<br />
                root = new BTreeNode(item);<br />
<br />
            }<br />
            else<br />
                Insert(item, root);<br />
        }<br />
<br />
        // pre: ptr != null<br />
        // post: item is inserted to the binary search tree rooted at ptr<br />
        private void Insert(IComparable item, BTreeNode ptr)<br />
        {<br />
            if (item.CompareTo(ptr.Item) < 0)<br />
            {<br />
                if (ptr.LChild == null)<br />
                {<br />
                    ptr.LChild = new BTreeNode(item);<br />
<br />
                }<br />
                else<br />
                    Insert(item, ptr.LChild);<br />
            }<br />
            else<br />
            {<br />
                if (ptr.RChild == null)<br />
                {<br />
                    ptr.RChild = new BTreeNode(item);<br />
<br />
                }<br />
                else<br />
                    Insert(item, ptr.RChild);<br />
            }<br />
        }<br />
<br />
        // there are three cases to consider:<br />
        // 1. the node to be deleted is a leaf<br />
        // 2. the node to be deleted has only one child <br />
        // 3. the node to be deleted has both left and right children<br />
        public void Delete(IComparable item)<br />
        {<br />
            // search for item and its parent<br />
            BTreeNode ptr = root; // search reference<br />
            BTreeNode parent = null; // parent of ptr<br />
            while ((ptr != null) && (item.CompareTo(ptr.Item) != 0))<br />
            {<br />
                parent = ptr;<br />
                if (item.CompareTo(ptr.Item) < 0) // move to the left child of ptr<br />
                    ptr = ptr.LChild;<br />
                else<br />
                    ptr = ptr.RChild;<br />
            }<br />
<br />
            if (ptr != null) // if the search was successful<br />
            {<br />
                // case 3: item has two children<br />
                if ((ptr.LChild != null) && (ptr.RChild != null))<br />
                {<br />
                    // find the right-most node in left subtree of ptr<br />
                    if (ptr.LChild.RChild == null) // a special case: the right subtree of ptr.LChild is empty<br />
                    {<br />
                        ptr.Item = ptr.LChild.Item;<br />
                        ptr.LChild = ptr.LChild.LChild;<br />
                    }<br />
                    else<br />
                    {<br />
                        BTreeNode p = ptr.LChild;<br />
                        BTreeNode pp = ptr; // parent of p<br />
                        while (p.RChild != null)<br />
                        {<br />
                            pp = p;<br />
                            p = p.RChild;<br />
                        }<br />
                        // copy the item at p to ptr<br />
                        ptr.Item = p.Item;<br />
                        pp.RChild = p.LChild;<br />
                    }<br />
                }<br />
                else // cases 1 & 2: item has no or only one child<br />
                {<br />
                    BTreeNode c;<br />
                    if (ptr.LChild != null)<br />
                        c = ptr.LChild;<br />
                    else<br />
                        c = ptr.RChild;<br />
<br />
                    // remove node ptr<br />
                    if (ptr == root) //need to change root<br />
                        root = c;<br />
                    else<br />
                    {<br />
                        if (ptr == parent.LChild)<br />
                            parent.LChild = c;<br />
                        else<br />
                            parent.RChild = c;<br />
                    }<br />
                }<br />
<br />
            }<br />
        }<br />
<br />
        public void PreOrderTraverse()<br />
        {<br />
            //Console.Write("PreOrder: ");<br />
            PreOrderTraverse(root);<br />
            Console.WriteLine();<br />
        }<br />
<br />
        private void PreOrderTraverse(BTreeNode root)<br />
        {<br />
            if (root != null)<br />
            {<br />
                Console.Write(root.Item);<br />
                PreOrderTraverse(root.LChild);<br />
                PreOrderTraverse(root.RChild);<br />
            }<br />
        }<br />
<br />
        public void InOrderTraverse()<br />
        {<br />
            //Console.Write("InOrder: ");<br />
            InOrderTraverse(root);<br />
            Console.WriteLine();<br />
        }<br />
<br />
        private void InOrderTraverse(BTreeNode root)<br />
        {<br />
            if (root != null)<br />
            {<br />
                InOrderTraverse(root.LChild);<br />
                Console.WriteLine(root.Item);<br />
                InOrderTraverse(root.RChild);<br />
            }<br />
        }<br />
<br />
        public void PostOrderTraverse()<br />
        {<br />
            //Console.Write("PostOrder: ");<br />
            PostOrderTraverse(root);<br />
            Console.WriteLine();<br />
        }<br />
<br />
        private void PostOrderTraverse(BTreeNode root)<br />
        {<br />
            if (root != null)<br />
            {<br />
                PostOrderTraverse(root.LChild);<br />
                PostOrderTraverse(root.RChild);<br />
                Console.Write(root.Item);<br />
            }<br />
        }<br />
<br />
        public void Clear()<br />
        {<br />
            root = null;<br />
        }<br />
<br />
        // pre: true<br />
        // post: Return all items in the collection<br />
        public ArrayList AllItems()<br />
        {<br />
            ArrayList items = new ArrayList();<br />
            AllItems(root, items);<br />
            return items;<br />
        }<br />
<br />
        private void AllItems(BTreeNode root, ArrayList keys)<br />
        {<br />
            if (root != null)<br />
            {<br />
                AllItems(root.LChild, keys);<br />
                keys.Add(root.Item);<br />
                AllItems(root.RChild, keys);<br />
            }<br />
        }<br />
}<br />
<br />
// the main method <br />
using System;<br />
using System.Collections;<br />
<br />
namespace PatientName<br />
{<br />
    class Program<br />
    {<br />
        static void Main(string[] args)<br />
        {<br />
            int choice;<br />
            IPatient p1 = new Patient();<br />
            IBSTree container = new BSTree();<br />
            Console.WriteLine("Enter the first Name of the patient:");<br />
            p1.FirstName = Console.ReadLine();<br />
            container.Insert(p1);<br />
                    <br />
        }<br />
    }<br />
}<br />
<br />
<br />

Guffa29-Apr-08 2:52

Guffa

29-Apr-08 2:52

Tip: Use the pre tag when posting blocks of code. It makes it readable.

As far as I can see you only have overloads of the Insert method that takes an IComparable parameter. The Patient class doesn't implement the IComparable interface. Even if it would, the variable p1 is an IPatient reference, so it can never be used as an IComparable reference even if the actual ojbect would implement the IComparable interface.

Make the Patint class implement the IComparable interface, and change the variable p1 from an IPatient reference to a Patient reference.

Despite everything, the person most likely to be fooling you next is yourself.

I tried tht earlier and i gott this error "Patient cannot implement interface member System.IComparable.CompareTo(Object)"

ADTC#29-Apr-08 3:02

Re: I tried tht earlier and i gott this error "Patient cannot implement interface member System.IComparable.CompareTo(Object)"

29-Apr-08 3:02

<pre>
//here is the IPatient implementation
using System;
using System.Collections;

public class Patient: IPatient, IComparable
{
private string fname;

public string FirstName
{
get
{
return fname;
}
set
{
fname = value;
}
}
public int CompareTo(Patient obj)
{
//Patient p1 = (Patient)obj;
return fname.CompareTo(p1.fname);
}
}

//the main method
using System;
using System.Collections;

namespace PatientName
{
class Program
{
static void Main(string[] args)
{
int choice;
Patient p1 = new Patient();
BSTree container = new BSTree();
Console.WriteLine("Enter the first Name of the patient:");
p1.FirstName = Console.ReadLine();
container.Insert(p1);

}
}
}

</pre>

J a a n s29-Apr-08 3:06

yet another one cropped up

29-Apr-08 3:06

The signature of CompareTo method will change like this

public int CompareTo(object obj){

You have to include a type checking of obj also

*jaans

ADTC#29-Apr-08 3:14

Re: yet another one cropped up

29-Apr-08 3:14

And if i traverse the BST and try to output whats stored in BST it displays the Name of the ADT in my case "Patient" instead of the name of the people

J a a n s29-Apr-08 3:28

29-Apr-08 3:28

You are using Console.WriteLine(root.Item); for output, but

root.Item<br />

is holding an IPatient object, so its displaying the type name itself.

If you want to display the FirstName cast the object and use the suitable properties.

*jaans

Thank you

ADTC#29-Apr-08 4:30

Re: The best overload method match system.IComparable has invalid arguments

29-Apr-08 4:30

Thanks a million

J a a n s29-Apr-08 2:54

Doesnot implement interface member System.IComparable.CompareTo(Object)

29-Apr-08 2:54

Modify your interface to implement IComparable interface

public interface IPatient:IComparable
{
//Pre: true
//Post: return the first name of the patient
string FirstName { get; set; }
//Pre: true
//Post: return the last name of the patient
//string LastName { get; set; }
}

You may have to change your implementation of Patient class also accordingly.

*jaans

ADTC#29-Apr-08 3:06

Re: Doesnot implement interface member System.IComparable.CompareTo(Object)

29-Apr-08 3:06

Yes i tried the solution you gave me earlier so i was wondering if i missed out something.
i get another error:
Doesnot implement interface member System.IComparable.CompareTo(Object);

J a a n s29-Apr-08 3:09

yet another one cropped up

29-Apr-08 3:09

see my comment to your earlier post.

*jaans

ADTC#29-Apr-08 3:19

29-Apr-08 3:19

And if i traverse the BST and try to output whats stored in BST it displays the Name of the ADT in my case "Patient" instead of the name of the patient.

Installation

coders_need29-Apr-08 1:14

coders_need

29-Apr-08 1:14

I have 3 doubts
1. I want to install DOTNET latest version in my computer. I dont have CD for installation. Which website would you suggest to get this done.

General Doubts

2. How to create
Internet and Show Desktop symbols on status bar

3. How to include
My Computer, My Documents , Network Neighbour symbols on desktop

Re: Installation

J a a n s29-Apr-08 1:25

How to use regular expression

29-Apr-08 1:25

What this has to do with c#?

Anyway the answers...
1. Microsoft download site
2. On status bar of what?
3. Use desktop properties

*jaans

Re: Installation

Vikram A Punathambekar29-Apr-08 2:17

Vikram A Punathambekar

29-Apr-08 2:17

1. Google.
2. Whose status bar?
3. TweakUI.

Cheers,
Vikram.

The hands that help are holier than the lips that pray.

Exelioindia29-Apr-08 0:07

Exelioindia

29-Apr-08 0:07

Hi,

In my web application i am using a text area. How to display the & as & < as < , is there any way rather than using string.replace??

Please suggest me, if possible give me some link where i can learn.

Thanks in advance

Know is Drop, Unknown is Ocean

c242329-Apr-08 0:48

c2423

29-Apr-08 0:48

You can try
& amp for ampersand (without the space)
AND
& lt for less than (without the space)
A quick way to look these up is to get a blank web page (aspx extension), type the symbols you want in "design" view, switch to "source" view and copy/paste the generated code for the symbol.

For example I put the characters onto a webpage and switched to source and got:
<form id="form1" runat="server">
<div>
&<br />
<</div>
</form>

Hope this helps
Chris

p.s. next time, this might be better in the Asp.Net forum rather then the C# forum

[Edit: My careful formatting doesnt seem to have copied very nicely so modified the post!]

Exelioindia29-Apr-08 1:05

Exelioindia

29-Apr-08 1:05

Thank you very much for spending your valuable time and helping me. But i am expecting a better solution

Know is Drop, Unknown is Ocean

Pete O'Hanlon29-Apr-08 0:51

Pete O'Hanlon

29-Apr-08 0:51

You can always use HttpUtility.HtmlDecode to convert your HTML text back into normal text, however you really need to think about whether this is what you want to do. The whole point of HTML encoded text is to have something that will display in a web browser, so < is not the same as < - until the point you convert it using HtmlDecode.

Deja View - the feeling that you've seen this post before.

My blog | My articles