problem of controls array in Visual Basic 2005

problem of controls array in Visual Basic 2005

• Jim Perry

  For Each Cnl As Control In Grl.Controls

  If Cnl.Tag = Chk.Tag Then

  If TypeOf Cnl Is ComboBox Then

  Grl.Controls.Remove(Cnl)

  End If

  End If

  Next

  
  
  The ForEach loop goes through the index from 0 to 2, so the first loop = item with index0, the second loop = item with index1, the third loop = item with index2
  
  But if you remove itemA during the first loop, then itemB becomes the item at index0 and itemC=index1, so when the foreach loop goes to the second loop, it's looking for item with index1 which is itemC at that time.
  
  In other words, don't use a ForEach loop if you're removing items - use a For..To.. loop instead.
  
  

• lali.b

  Actually, Blair Allen Stark gave you a hint for linking the parent-checkbox to each child-combobox: by pointing the combobox's tag to the parent-checkbox, you don't have to mess with indexnumbers because the tag points to the whole parent-checkbox object. So you would get this code:
  Combobox1.Tag = CheckBox1
  
  ------
  I don't quite understand what you mean by 'determine if the control is numerical or not , required or not'.
  
  -----
  If you only want to save comboboxes that have numerical values (at the start of the text), then use the IsNumeric function: zTrueOrFalse = IsNumeric(combobox1.text)
  Note that the IsNumeric function still returns True if there are words in the text after a number at the start. http://msdn2.microsoft.com/en-us/library/6cd3f6w1.aspx
  
  -----
  If you want a way to link the parent-CheckBox to its children-comboboxes, then you could use some type of Collection object to store the comboboxes, and make that collection object the Tag of the Checkbox. For Example:
  
  Dim zHashTable As Hashtable
  Dim zComboBox As ComboBox
  
  zHashTable = New Hashtable ' This hashtable collection will store the Child-ComboBoxes
  CheckBox1.Tag = zHashTable ' Attach the hashtable-collection to the checkbox' Tag
  
  zComboBox = New ComboBox ' This adds a new child-combobox
  zComboBox.Tag = CheckBox1 ' Point the new combobox' .Tag to the parent-checkbox
  
  ' Add the combobox to the GroupBox
  GroupBox1.Controls.Add(zComboBox)
  
  ' Put the child-combobox into the parent-checkbox's hashtable-collection of children
  ' the zComboBox object is used as both key and value
  zHashTable.Add(zComboBox, zComboBox)
  
  ' Now removing the Combobox again
  GroupBox1.Controls.Remove(zComboBox)
  zHashTable.Remove(zComboBox)
  
  Now you have linked each combobox to its parent-checkbox, and each parent-checkbox carries a collection of its child-comboboxes in its own Tag property.
  
  
  
  

• alihht

  Blair,

  If you claim "VBsux's" so much. Why do you hang around VB fora to criticize it

  I don't like C languages but I don't go into C fora to criticize the language. It's a lot like going to christian fora to criticize christians. Your role becomes that of a troll. Even with all of your talents, your role in VB fora is often that of a troll.

  
  
  

• Kenneth Gillen

  mm_ezzo wrote:

  thans blair for yuor replay but i have some problem with tag property that's cause me don't use it any more to determine the control Actualy i use it to determine if this control is required or not when i validates the controls before saving the data i need any other way to detemine the control in array of controls in container but first i need the way to set the index to control before i create it and before set the name prperty to it !! note: i'm trying to learn C# but i have no time for that .... maybe later thanks again

  easy. . .

  public partial class Form1 : Form { public Form1() { InitializeComponent(); checkBox1.Tag = new ControlWrapper(textBox1); checkBox2.Tag = new ControlWrapper(textBox2); checkBox3.Tag = new ControlWrapper(textBox3); textBox1.Tag = new ControlWrapper(comboBox1); textBox2.Tag = new ControlWrapper(comboBox2); textBox3.Tag = new ControlWrapper(comboBox3); checkBox1.CheckedChanged += checkBox1_CheckedChanged; checkBox2.CheckedChanged += checkBox1_CheckedChanged; checkBox3.CheckedChanged += checkBox1_CheckedChanged; } void checkBox1_CheckedChanged(object sender, EventArgs e) { CheckBox cb = sender as CheckBox; if (cb == null) return; ControlWrapper wrapper = cb.Tag as ControlWrapper; if (wrapper == null) return; TextBox tb = wrapper.Control as TextBox; if (tb == null) return; wrapper = tb.Tag as ControlWrapper; if (wrapper == null) return; ComboBox cbo = wrapper.Control as ComboBox; if (cbo == null) return; tb.Text = cb.Checked cbo.Text : string.Empty; } } public class ControlWrapper { bool _isRequired = true; Control _ctrl; public ControlWrapper(Control ctrl, bool isRequired) { _ctrl = ctrl _isRequired = isRequired; } public ControlWrapper(Control ctrl):base(ctrl, true){}; public Control Control { get { return _ctrl; }} public bool IsRequired { get { return _isRequired;} {set { _isRequired = value;} } }

  
  
  

• maverick_majnoo

  Thanks nogchoco

  i mean by 'determine if the control is numerical or not , required or not'

  actualy i useing module it's contain procedures and functions and use it from the forms :

  like :

  public sub ValidTheForm(ByVal F as Form)

  'for each control in form F do validthecontrol procedure

  end sub

  private sub ValidTheControl( ByVal C as Control)

  if c.tag="m" then ' it's required so show messagebox to user to must fill it.

  if c.tag="i" then ' it numerical and user must insert only numbers

  ' ....................etc

  end sub

  and in the form i write code like this :

  sub save

  validtheform(me)

  end sub

  actualy i have no idea about the the hashtable but i will work with it and i will feedback to u

  Thank You again

  
  

• Blkbird

  The indexproblem is as I described it: removing an item from a collection makes the index of the other items decrease by 1 and so the ForEach loop skips an item because it doesn't take the reordering of the items into account.

  Here's a working example for you. It's a Form1 with 2 checkboxes: Chk (with Tag=1) and Chk2(with Tag=2) and a Groupbox (named Grl). Note that I don't have your complete code, so I had to adapt it slightly to make it work. The eventsub handles checkstatechanges for both checkboxes so I've used "sender" (which is one of the checkboxes) as the object. Just start a new WindowsApplication, add two checkboxes and a groupbox, name and tag them as mentioned, and paste the code below as the code for Form1.

• Lixin wang

  You're welcome, mm_ezzo
  
  

• Tom_Liu

  thans blair for yuor replay

  but i have some problem with tag property that's cause me don't use it any more to determine the control

  Actualy i use it to determine if this control is required or not when i validates the controls before saving the data

  i need any other way to detemine the control in array of controls in container

  but first i need the way to set the index to control before i create it and before set the name prperty to it !!

  note: i'm trying to learn C# but i have no time for that .... maybe later

  thanks again

  
  

• Donald E. King

  Thanks nogchoco

  hashtable is WonderFull Way to do what i want.....

  thank u

  
  

• stallion_alpa

  actually. . . control arrays were VbSux's way of gettng around some of its major deficiencies.

  the proper way to do this would be to assign the associated textbox to the checkbox.tag and assign the associated combobox to the text box tag

  in a checkedchanged handler cast the sender to a checkbox and cast tthat's tag to a text box and cast thats's tag to a combo box. then set the casted textbox text to the casted combobnoxes tag

  because I can't stand coding in VB, this is in c# but the idea is the same. . . NOTE when you see the code in vb and compare to c# you will see why I dont care for vb.

  public partial class Form1 : Form { public Form1() { InitializeComponent(); checkBox1.Tag = textBox1; checkBox2.Tag = textBox2; checkBox3.Tag = textBox3; textBox1.Tag = comboBox1; textBox2.Tag = comboBox2; textBox3.Tag = comboBox3; checkBox1.CheckedChanged += checkBox1_CheckedChanged; checkBox2.CheckedChanged += checkBox1_CheckedChanged; checkBox3.CheckedChanged += checkBox1_CheckedChanged; } void checkBox1_CheckedChanged(object sender, EventArgs e) { CheckBox cb = sender as CheckBox; if (cb == null) return; TextBox tb = cb.Tag as TextBox; if (tb == null) return; ComboBox cbo = tb.Tag as ComboBox; if (cbo == null) return; tb.Text = cb.Checked cbo.Text : string.Empty; } }

  
  
  

• djchapin

  Thank u Blair
  

• Vivek Uppal

  Thanks nogchoco : for your replay..

  actualy : i tryed to do as u sayed but the problem still persist .

  the problem is : more than one control of controls in groupbox have the same index

  and some indexes missed :

  example : in groupbox it have 50 control but there's no element have index 16 !

  i don't know why

  And your way here will cause error !!

  any way to set the index to elements in container when creates the elements before i set the name to it

  thanks again

  
  

• Simon.Chan

  Hear Hear.....

  Everyone has a personal opinion but I wholeheartedly agree with Renee comment. Expressing your own personal opinions like this in a forum dedicated to the product - only serves to start arguments/flames.

  Whilst you entitled to your opinion I would respectfully request that you dont express them in such a public manner in these forums. It just isnt needed and doesnt add anything to your comments.

  
  

• jeff1024

  Thanks nogchoco

  it's works

  thank you very much

  but could i ask you something else

  i use the tag property for determine if the control is numerical or not , required or not .

   as  a validation method before saving the data

  there's any way else instead of tag property to derermine the control in the container .

  but befor determination i need to set th index to the control before  or when i create it.

   

  Thank you again

   

  
  
• problem of controls array in Visual Basic 2005