Array Structure Help

Array Structure Help

• LouisPeter

  In reading through this thread, it appears the root of the problem is that your arrays are not declared with a dimension. Since you created empty arrays, they need to be redimensioned before you can start assigning values. If you don't know what the size of the array needs to be when it is declared, you might consider using an ArrayList, List(Of T), or strongly typed collection object instead of just an array. Then you don't have to worry about the size of the collection. You should at least use the collection privately within the structure - if you want to expose an array of values from the structure, use the ToArray() method of your collection in a readonly property on the structure.

  Also, since these are globally shared variables, it may be that some other code routine is changing your arrays. Global variables should be avoided whenever possible for just this reason. It is much better to pass an instance of the object between forms rather than declare the object globally.

  
  
  

• Sumesh Nair

  ok thanks dman that did help, however now it has created another error for me.
  
  When i enter all my values and hit show all to show all the entered information in my list box on the main form it presents me with a "NullReferenceException was unhandled" error.
  
  It highlights this code ...
  
  For X = 0 To gCtr
  Line = Data(X).gName.PadLeft(0) & Data(X).gScore.ToString.PadLeft(7) _
  & Data(X).gGender.ToString.PadLeft(15) & Data(X).gDean.ToString.PadLeft(15)
  lstData.Items.Add(Line)
  Next X
  
  
  

• furjaw

  Then your first element of the array or one of its items has not been declared...repost the corrrected code and we will go from there....

  Dim Data(NumRecords) as Entry

  Dim gCtr as Integer = 0

  Data(gCtr).gName = txtName.Text
  Data(gCtr).gScore = Decimal.Parse(txtScore.Text)
  Data(gCtr).gGender = GenderTemp
  Data(gCtr).gDean = DeanTemp

  This code only sets element zero of the Data Array
  

  
  
  

• dvidal

  It's showing X as 0
  
  
  

• Stefan Wrobel

  frmMain code section
  'Counting number of entries
  gCtr = gCtr + 1
  
  'Preserve original array(s) and set variables
  ReDim Preserve Data(gCtr)
  
  Data(gCtr).gName = txtName.Text
  Data(gCtr).gScore = Decimal.Parse(txtScore.Text)
  Data(gCtr).gGender = GenderTemp
  Data(gCtr).gDean = DeanTemp
  
  My Globals
  Public Structure Entry
  Dim gScore As Decimal
  Dim gGender, gDean, gName As String
  End Structure
  Public Data() As Entry
  Public gCtr As Integer = -1
  Public Z, Max, K, X As Integer
  Public Heading, Divider, NameTemp, GenderTemp, DeanTemp As String
  Public ScoreTemp As Decimal
  
  
  

• hommer

  In the code above that you posted only the last element of the Data array gets filled(unless it is in a loop)...and that element number is gCtr

  Post the complete method that this code is in and I will better be able to help you

  'Counting number of entries
  gCtr = gCtr + 1
  
  'Preserve original array(s) and set variables
  ReDim Preserve Data(gCtr)
  
  Data(gCtr).gName = txtName.Text
  Data(gCtr).gScore = Decimal.Parse(txtScore.Text)
  Data(gCtr).gGender = GenderTemp
  Data(gCtr).gDean = DeanTemp
  

  
  
  

• Coritani

  If Data(0) to data(gCtr) has not been filled with values then you will get the null ref exception on your structure elements because they have not been explicitly set.....

  When it stops and highlights that line during debug...what is the value of X...

  
  
  

• rahulmanasa

  Is Entry.gName suppose to be a string value or an array of strings...it looks to me like it should be a single string value...that being the case then your structure should declare the elment without the parentheses....

  Public Structure Entry

  Dim gScore() As Decimal<-This is an array of decimals
  Dim gGender(), gDean(), gName() As String <-These are arrays of Strings

  End Structure

  Public Structure Entry

  Dim gScore As Decimal <----single decimal entry

  Dim gGender, gDean, gNameAs String <----single string entries

  End Structure

  You also can not declare the size of an array as -1

  
  Public NumRecords = 99

  Dim gCtr as Integer = 0

  Dim Data(NumRecords) as Entry <-------an array of entry containing 100 records

  Data(gCtr).gName = txtName.Text
  Data(gCtr).gScore = Decimal.Parse(txtScore.Text)
  Data(gCtr).gGender = GenderTemp
  Data(gCtr).gDean = DeanTemp
  

  
  
  

• AlexBB

  DMan1 wrote:

  In the code above that you posted only the last element of the Data array gets filled(unless it is in a loop)...and that element number is gCtr Post the complete method that this code is in and I will better be able to help you 'Counting number of entries gCtr = gCtr + 1 'Preserve original array(s) and set variables ReDim Preserve Data(gCtr) Data(gCtr).gName = txtName.Text Data(gCtr).gScore = Decimal.Parse(txtScore.Text) Data(gCtr).gGender = GenderTemp Data(gCtr).gDean = DeanTemp

  
  frmMain Code
  Click event for btnEnter
  

  'Validation
  If Validation() = False Then
  Exit Sub
  End If
  
  'Counting number of entries
  gCtr = gCtr + 1
  
  'Preserve original array(s) and set variables
  ReDim Preserve Data(gCtr)
  
  Data(gCtr).gName = txtName.Text
  Data(gCtr).gScore = Decimal.Parse(txtScore.Text)
  Data(gCtr).gGender = GenderTemp
  Data(gCtr).gDean = DeanTemp
  
  'Changes radbutton to display a gender and not a true/false statement
  If radMale.Checked = True Then
  GenderTemp = "M"
  Else
  GenderTemp = "F"
  End If
  
  Making checkbox state yes/no if on dean's list
  If ckbDean.Checked = True Then
  DeanTemp = "Yes"
  Else
  DeanTemp = "No"
  End If
  
  'Clear values for next input
  txtName.Clear()
  txtScore.Clear()
  radMale.Checked = False
  radFemale.Checked = False
  cboDep.Text = ""
  ckbDean.Checked = False
  lstData.Text = ""
  txtName.Focus()

• Array Structure Help