Need Help with SortedList<tkey,tvalue> [modified]

[gamer1127]

Hi. I'm now using the SortedList to sort the strings from the text file. Is it possible to have a single key as the basis for comparing each string? If yes, I want to know how i will prevent the key from duplicating. Can someone help me? As of now this is what I accomplished:

public static void SortByLastName(ref string[] arrayOfLastNames, ref string[] arrayOfFirstNames, ref string[] arrayOfPlateNum, ref string[] arrayOfType, ref string[] arrayOfYear)
{
Console.Clear();

        int vehicleCountInt = 0;

        Console.WriteLine("SHOW DATABASE: SORTING BY LAST NAME\\n");

        using (StreamReader countVehicle = new StreamReader("vehiclecount.txt"))
        {
            vehicleCountInt = Int32.Parse(countVehicle.ReadLine());

            countVehicle.Close();
        }

        SortedList sortedLastName = new SortedList(vehicleCountInt);
        
        using (StreamReader outputLastNames = new StreamReader("lastnames.txt"))
        {
            
            for (int i = 0; i < vehicleCountInt; i++)
            {
                arrayOfLastNames\[i\] = outputLastNames.ReadLine();

                string keyVal = arrayOfLastNames\[i\];

                sortedLastName.Add(keyVal, arrayOfLastNames\[i\]); //I'm having a run-time error here that throws the ArgumentException

                if (!sortedLastName.ContainsKey(keyVal))
                {
                    sortedLastName.Add(keyVal, arrayOfLastNames\[i\]);
                }
                else
                {
                    sortedLastName.Remove(keyVal);
                    sortedLastName.Add(keyVal, arrayOfLastNames\[i\]);
                }

                Console.WriteLine("{0}", sortedLastName.Keys\[i\]);//And sometimes throws the exception ArgumentOutOfRange Exception
            }
            
            
            outputLastNames.Close();
        }

    }

modified on Friday, September 4, 2009 11:47 AM

[Lost User]

gamer1127 wrote:

sortedLastName.Add(keyVal, arrayOfLastNames[i]); //I'm having a run-time error here that throws the ArgumentException

What information does the debugger show? The ArgumenException implies that one of the arguments to the sortedLastName.Add() call contains an invalid value, quite possibly null.

[gamer1127]

It says that an entry with the same key already exists.

[Gideon Engelberth]

gamer1127 wrote:

sortedLastName.Add(keyVal, arrayOfLastNames[i]); //I'm having a run-time error here that throws the ArgumentException if (!sortedLastName.ContainsKey(keyVal)) { sortedLastName.Add(keyVal, arrayOfLastNames[i]); } else { sortedLastName.Remove(keyVal); sortedLastName.Add(keyVal, arrayOfLastNames[i]); }

You did it wrong, then you did it right. Why do you even have the line that is getting the error? You are doing the same thing with the next if block.

gamer1127 wrote:

Console.WriteLine("{0}", sortedLastName.Keys[i]);//And sometimes throws the exception ArgumentOutOfRange Exception

You are getting this error for the same reason you were getting the previous error. If you have a duplicate key, you will not have "i" items in the list. You need to check if that many keys exist before trying to write them out. On an style note, it appears that you have several properties of items all stored in separate arrays, and a single array of a class (with FirstName, LastName, PlateNumber, Type, and Year properties) may be better. Also, there is no reason to pass the array by ref just to change the values in them. If you are passing the array by ref so you can change the length, I would suggest returning an array instead, since you do not seem to be using the data already in the arrays.

[gamer1127]

Gideon Engelberth wrote:

On an style note, it appears that you have several properties of items all stored in separate arrays, and a single array of a class (with FirstName, LastName, PlateNumber, Type, and Year properties) may be better.

Can you please show an example for that? By the way, I already solved the problems. I'll get back to you guys when a new problem comes up. :laugh:

[gamer1127]

What if there are values that are the same? How will I show those two? I know that they must have different keys but how will I exactly do that? For example:

Hibaler
Balde
Metin
Dela Vega
Dimagiba
Pederoso
Dinulos
Du
Gotengco
Lira
Guban
Garraez
Carpena
Reyes //first value
Zulueta
Gonzalez
Isidoro
Marfa
Reyes //second value
Guinhawa
Aaron
Lazaro
Obsum
Molino
Estenor
Nolasco
Paral
Porillo
Novillos
Alihan

How will I assign different values for the other so i can show them both after sorting?

[Luc Pattyn]

why are you making everything much more complex than necessary? dictionaries (SortedList is a dictionary) require keys to be unique, which does not match your application; so forget about dictionaries as your primary storage. you can keep a list of strings (any strings including duplicates) in a List<string> which you can simply sort by calling myList.Sort() you can also define your own little class "MyType" (holding name, age, address, vehicleColor, whatever) and collect those in a List<MyType> Strings get sorted alphabetically by default; your own objects don't have a default sort order. If you need a (special) sort order (i.e. non-alphabetic for strings) you can easily do that with an object that implements IComparable; I wrote a little article[^] that explains it all. FWIW: I strongly recommend you buy and study a book on C# to increase your basic knowledge of the language and the .NET framework. Here[^] is why. :)

Luc Pattyn

:badger: :jig: :badger:

Have a look at my entry for the lean-and-mean competition; please provide comments, feedback, discussion, and don’t forget to vote for it! Thank you.

:jig: :badger: :jig:

[gamer1127]

Luc Pattyn wrote:

why are you making everything much more complex than necessary?

My answer to that is because the program that i'm creating is for the subject that i have about data structures. I can't use Array.Sort() etc because the solution that we presented is to use radix sort(which i didn't continue because I can't resolve the error i always get). We have a different subject for the fundamentals and other things about C#. But I'll take your advice. I already visited the links that you posted and read it especially about learning a new language. I already have a book, the title: C# Programming: From Program Analysis to Program Design by Barbara Doyle. But probably I'll do what you said there so I can have more knowledge about the language. :-D

[Luc Pattyn]

OK Now SortedList is not dealing with duplicate keys and not doing Radix Sort, so it is a bad choice. What you need is create your own collection class, probably inheriting from List<string> or List<MyType>, start by using its normal Sort method, later on override the Sort method with your own (for which I already gave the basic principles in another thread). :)

Luc Pattyn

:badger: :jig: :badger:

Have a look at my entry for the lean-and-mean competition; please provide comments, feedback, discussion, and don’t forget to vote for it! Thank you.

:jig: :badger: :jig: