VB.NET: I Cant find the index of an array

Question

This is the code for my array (which is working)

Public numUsers As Integer
Public fNameUsers As String = ("..\..\..\users.txt")
Public UserRecords As Usersclass() 'note... this line is in a module '

reader = New System.IO.StreamReader(fNameUsers)
numUsers = 0

   'Split the array up at each delimiter of "," and add new objects '
            Do While reader.Peek <> -1
                ReDim Preserve UserRecords(numUsers)
                oneline = reader.ReadLine
                fields = oneline.Split(",")
                UserRecords(numUsers) = New Usersclass
                UserRecords(numUsers).AccountNumber = fields(0)
                UserRecords(numUsers).CourseName = fields(1)
                UserRecords(numUsers).FirstName = fields(2)
                UserRecords(numUsers).LastName = fields(3)
                UserRecords(numUsers).DOB = fields(4)
                UserRecords(numUsers).Email = fields(5)
                UserRecords(numUsers).CourseProgress = (6)
                UserRecords(numUsers).AdminCheck = fields(7)

                numUsers = numUsers + 1

            Loop
            reader.Close()

My problem is that I don't know how to lookup the index of an array where the .accountNumber = a variable. For example the acccountNumber is 253, what is the code to find the index this relates to????

Thanks in advance

Answer 1

Write a search function, loop through the Array and return the index if you've found the specified record. Or you use a Dictionary, like

  Public UserRecords As New Dictionary(Of Integer, Usersclass)

which you could use like this

  Dim desiredUser As Usersclass = UserRecords(hisAccountNumber)

Answer 2

You would be better off dropping the use of arrays and instead look at dictionary objects.

A dictionary in laymans terms is very similar to an array but you can locate an object using a key, in your case the account number.

             Dim UserRecords as  New Dictionary(Of String, Usersclass)
             Dim UserRecord as Userclass
             Do While reader.Peek <> -1

                oneline = reader.ReadLine
                fields = oneline.Split(",")

                'Populate your class
                UserRecord = New Usersclass
                UserRecord.AccountNumber = fields(0)
                UserRecord.CourseName = fields(1)
                UserRecord.FirstName = fields(2)
                UserRecord.LastName = fields(3)
                UserRecord.DOB = fields(4)
                UserRecord.Email = fields(5)
                UserRecord.CourseProgress = (6)
                UserRecord.AdminCheck = fields(7)

                'Add to the dictionary here
                UserRecords.Add (fields(0),UserRecord)

            Loop

            ''Then find your UserRecord by the accountnumber e.g
            UserRecord = UserRecords("253")

Answer 3

A Dictionary object is probably exactly what you're looking for. It let's you set you own key innstead of using an array index. I don't write much VB but here's what it would look like in c#:

//Create the dictionary
Dictionary<int, Account> userRecords = new Dictionary<int, Account>();

//Add an account to the dictionary
userRecords.Add( accountNumber, account );

//Get an accoutn out of the dictionary
Account account = userRecords[accountNumber];

Answer 4

Do While reader.Peek <> -1
                    ReDim Preserve UserRecords(numUsers)
                    oneline = reader.ReadLine
                    fields = oneline.Split(",")
                    UserRecords(numUsers) = New Usersclass
                    UserRecords(numUsers).AccountNumber = fields(0)
                    UserRecords(numUsers).CourseName = fields(1)
                    UserRecords(numUsers).FirstName = fields(2)
                    UserRecords(numUsers).LastName = fields(3)
                    UserRecords(numUsers).DOB = fields(4)
                    UserRecords(numUsers).Email = fields(5)
                    UserRecords(numUsers).CourseProgress = fields(6)
                    UserRecords(numUsers).AdminCheck = fields(7)
                    UserRecords(numUsers).password = fields(8)

                    numUsers = numUsers + 1

                Loop