I'm working on an assignment that takes in 20 answers from user using 20 textboxes, grade the answers and output the correct answer choices to 20 label boxes. The input answers and the answer keys are store in array. What's the best method to pass values from the answer key array to all appropriate labels in the form? Right now I'm using this method:
For i As Integer = 21 To intLblNum
For intCount = 0 To (strAnswers.Length() - 1)
gradeResult.Controls("Label" & i.ToString).Text = strAnswers(intCount)
Next
Next
But as the result, all of my label boxes contain only the last element from the answer key array. What'd I do wrong?
One problem that I see is that you loop through all 20 answers for each label, you need to have one loop and offset the value to account for your Label names. Something like this should work for you.
Dim maxEntrys As Integer = 19
For i = 0 To maxEntrys
gradeResult.Controls("Label" & (21 + i)).Text = strAnswers(i)
Next
Assuming you are in WinForms, each controls has a Tag property of type object that can be used to store custom data. It is not considered good design to use control naming as a means of associating data with controls.
Consider using a class to hold your question/answer data, make an array or preferably collection of them and set each control's Tag property to the appropriate instance.
Related
My program creates an array of checkboxes at runtime as shown below:
For Looper = 0 To 36
Dim Ex1ConfigCheck As New CheckBox
frmSetup.Controls.Add(Ex1ConfigCheck) ' Add Control to from
Ex1ConfigCheck.Top = (Looper + 45) + (Looper * 18) ' Set Location
Ex1ConfigCheck.Left = 210
Ex1ConfigCheck.Text = Setup.ExCheckName(Looper) ' Set Text property from strArray
Next
This is where I don't know how to proceed.
I would like to fill a boolean array (ex. MyBoolean(37)) with the value of Ex1configCheck().Checked. The reason I would like to fill another array is because I need to be able to reference the value of the checkboxes in other parts of the code but can't access them until they are created. Also, I plan on saving the array out to a binary file.
Could someone point me in the right direction please?
If there are no other CheckBoxes in the same container as those ones then you can do this:
Dim flags = Me.Controls.OfType(Of CheckBox)().
Select(Function(cb) cb.Checked).
ToArray()
If the controls are in a different container than the form itself, replace Me with that container.
As suggested by #Jimi, you could also create a List(Of CheckBox) and assign that to a field, populating it when you create the controls. You can then use that list instead of creating one on demand:
Dim flags = myCheckBoxList.Select(Function(cb) cb.Checked).
ToArray()
Of course, if you know exactly how many CheckBoxes you are going to be adding, why do you need to wait until run time to create them? Why can't you create them at design time and then modify them at run time? You usually only create controls at run time if you don't know how many there will be until run time, but that seems not to be the case here.
Thanks all for your answers and comments. I always have a fear of being roasted when I ask what some may consider a simple question online.
I have found an alternative way of accomplishing my task. Instead of creating 8 "Arrays" of checkboxes, I have learned of a very simple control available called "CheckedListBox".
I really didn't need to create the checkboxes at runtime but was trying to find an easier way to create 8 groups of 37 checkboxes without having to manually name and set the properties of each one during design. I also wanted to be able to index them in my code to be able to update and read the value using simple loops. I could have done this by creating arrays of CheckBox but again, I would have had to manually initialize the arrays.
Once I found the CheckedListBox, I was able to accomplish what I want very quickly. I only had to set the properties of the 8 "groups" (CheckedListBox's) and fill them using the items property. The ListBox essentially created a List like Jimi suggested automatically and I can index thru each list with a loop as desired. Jimi's suggestion actually lead me to finding the CheckedListBox while I was searching for more information on using "List(of CheckBox)".
Sometimes talking to others helps me find the right questions to ask. Google was able to figure out what I wanted when I searched for "List(of CheckBox)". (:
In excel I could say =INDIRECT("A" & G3) where G3 had a value of 4 and my cell would then refer to A4. What I am looking for is a similar kind of function for VB.net.
Is there a way to refer to a different variable based on a variable. EG. first pass I was to refer to txtJobNum1, txtBatNum1, and lblBat1. on pass two txtJobNum2, txtBatNum2, and lblBat2. If it were only a few, 3-4 maybe, it wouldnt be bothersome, but it's 50. The best I have come up with now to work around is build a class that holds references to those objects and make an array of that class. Below is an example table showing What I want to make with a given input number.
You can see how if I could make use of an "INDIRECT" function It could potentially shrink down to a 5-6 line loop instead of 200 lines of just variable assignments.
my concept of how it would work
BatchGroups(<NUMBER>).Label = lblBatNum<NUMBER+1>
0 BatchGroups(0).Label = lblBatNum1
0 BatchGroups(0).Number = txtBatNum1
0 BatchGroups(0).Quantity = txtQtybat1
0 BatchGroups(0).JobNumber = txtJobNum1
1 BatchGroups(1).Label = lblBatNum2
1 BatchGroups(1).Number = txtBatNum2
1 BatchGroups(1).Quantity = txtQtybat2
1 BatchGroups(1).JobNumber = txtJobNum2
2 BatchGroups(2).Label = lblBatNum3
2 BatchGroups(2).Number = txtBatNum3
All of the controls are stored in the Controls collection of their parent, and the controls in the Controls collection are addressable by name, like this:
Dim theControl As Control = Me.Controls("txtJobNum" & theNumber)
(Where Me is the Form) If the controls are in some other container control, such as a panel, you can get to them through that container control's Controls property, for instance:
Dim theControl As Control = MyPanel.Controls("txtJobNum" & theNumber)
However, having 50 some-odd controls like that sounds like it may be a bad design anyway. It may be better to consider having a grid, or an editable list of some sort. If you must have all of the separate controls like that, it would probably be better to dynamically load them in a loop, and then store references to them in a list of BatchGroup objects as you were thinking. It would be much easier to to that in a loop because you'd only write the code once rather than separately for each batch group.
More generally, the term in .NET for what you are asking is called "Reflection". However, using reflection can cause your code to be more brittle and it is also not very efficient, so, when there are other alternatives, is is the case here, it is usually best to take one of them, rather than resorting to reflection.
Create a dictionary of your objects by Name. Then use TryGetValue to retrieve. In this case it would expect a String value as a Key, so you can have a custom naming scheme, which maps 1-to-1 onto your controls list.
Read more about a Dictionary class on MSDN:
Dictionary(Of TKey, TValue) Class
You could use .Controls of the parent container, but then your controls could be nested in each other, so you'd have to use recursion or linearize into flat list, either adds complexity and maintainbility effort, and reduces performance. Dictionary is the fastest, especially if your Key is a string.
Hey guys very new here.
Have a listbox that gets account names from a specific game server using this command line
Dim apikeyinfo As APIKeyInfo = api.getApiKeyInfo()
lstbxCharacters.DataSource = apikeyinfo.Characters
this code gets all the characters in a single account by displaying it in a listbox.
Now i would like to reference a character from the lisbox but not sure how
Any method such as Listbox.Get to get the value and compare it with something else?
Thanks
you can try something like
lstbxCharacters.SelectedItem
Update
To read the data from the listbox I think there are multiple ways (Assuming that it is readable).
-> Usually listbox display strings, so it should work to read to a string variable
Dim a_string as Strin = lstbxCharacters.SelectedItem
also you may like to add a small check before, assuring that an Item is currently selected:
If lstbxCharacters.SelectedIndex < 0 then return
This jumps out of current sub if no item is selected
And finally, to read the first entry, you can also do it this way:
a_string = lstbxCharacters.Items(0)
if it returns objects, then instead of accessing the object directly, it may work to do
a_string = lstbxCharacters.Items(0).ToString
(most objects allow a .ToString() Function )
Here two ideas for different solutions:
As a user commented, you could access the DataSource directly + the information which listIndex was selected. But if you do so, then maybe it is more easy (if you need to access it anyways, to go with solution 2)
Create a variable of type list(Of some_object) and fill it with the data from the datasource. It will take some time to do this, but if you define for the class some_object a function ToString, then you can fill all objects directly to the lstbxCharacters, and access them without any worries, by doing CType(lstbxCharacters.SelectedItem, some_object)
Update 2
If with reference you mean to access further information from the datasource, then you need to build some kind of query, or set the content of the listbox in relation to another control that shows the database content (in that way the listbox lstbxCharacters would act like a filter)
Using 3.5 VB1 framework.net
I'm trying to add an element to an array
i would like to clear the listbox and display the array contents in listbox.
then add another button, then add an element to the array, from the textbox.
Ive created this painstakingly for the past 6 hours
Call clearout() ''===== Clears listbox
Dim MyNumbers(4) As Integer
Dim i As Integer
MyNumbers(0) = 1
MyNumbers(1) = 2
MyNumbers(2) = 3
MyNumbers(3) = 4
MyNumbers(4) = 5
For i = 0 To 4
ListBox1.Items.Add(MyNumbers(i))
Next i
That part works great!
It plops it right into listbox and deletes any previous entries into listbox
What Ive studied so far after all these hours to make the next button is to use UBound function to find the highest element then add one to it and ReDim it with that value
Problem is I'm not sure how to write that correctly under the second button
Any help?
I'm not quite clear what you are trying to achieve, but this is my interpretation:
Button1: clears the listboxpopulates the array with numbers 1 to 5populates the listbox with these numbers
Button 2: adds a number to the array from a textboxadds this new number from the array to the listboxORsimply increments the values in the array by 1 and append this new value to the listbox?
In any case, you need to share the array between the buttons so it must be declared with module level scope. That is, outside the button click routines.Also, in order to preserve the values already in the array, you need to use ReDim Preserve MyNumbers(newUBound)Hopefully the above tips will help!PS. Does your clearout() method simply call ListBox1.Items.Clear() ? If it does, it's best just to call this inline rather than create a new method to do this.
Let me provide a little detail to explain what I'm trying to accomplish before I get into the nuts and bolts of the question.
I've got two data sources - one is a SQL Server containing part numbers, descriptions, etc. The other is a CAD system that does not have a database in a traditional sense. What I'm trying to do is read out the bill of materials from the SQL Server and compare it to the CAD assembly drawing to ensure that the CAD system contains the same information as the SQL Server.
Getting the data from the SQL Server is fairly straight forward. I query the database and populate a datagrid. Done. Quick. Easy.
Getting the data from the CAD system is a little more involved. I have to load the assembly drawing to get a listing of all the component parts and then load those individual drawings to pull the "Part Number" property from the drawing. This is a somewhat time consuming and slow process (unfortunately) since each of the files must actually be accessed. I load those properties into an array (I guess a list might be more efficient).
So now I have a datagrid and array with part numbers. I need to compare them and colorize the grid accordingly. The grid should remain transparent if the part exists in both, color the row yellow if it only exists in the grid, and add a row colored red if only in the array.
As best I can tell, this means looping through the array on each line of the grid. The thought process is this:
Default the grid to yellow rows.
Loop through the grid and loop through the array to compare. If a match is found, make the row transparent and delete the element from the array.
After step 2 is completed, the array should only contain elements that are not found in the grid. Resize the array to remove the empty elements.
Add the elements of the array to the grid and color those new rows red.
The problems with this logic is that it seems expensive from a performance standpoint. Surely there is a better method? Also, if I modify the grid in some manner (like a resort) I have to go through the process again. I'd really appreciate some advice on this.
Thanks!
Note: written in Visual Studio 2005.
You could load the data from the CAD system in a dictionary (indexed by part number). Then you could go through the grid and check if it exists in the dictionary, which is a fast operation ( O(1) ). You could do exactly as you say, remove the found elements in the dictionary and add the remaining elements in the datagrid.
Here's some code for creating and using a dictionary (used C# style comments to preserve formatting):
//First argument is your key type, second is your item type
Dim cadParts As New Dictionary(Of Integer, Part)
//Add items to the parts dictionary
For Each part As Part In cadPartsArray
cadParts.Add(part.PartNumber,part)
Next
//Check if a part exists
Dim partNumber As Integer = 12345
If cadParts.ContainsKey(partNumber) ...
//Remove a part
cadParts.Remove(partNumber)
//Go through the remaining values
For Each part As Part In cadParts.Values ...
Edit:
1) Yes, if your key (here, part number) is a string, then a Dictionary(Of String,...) would be used.
2) I assumed you had a class named Part, which contained some information about a part. If you just have a part number, and no other info, then you could create a Hashset instead. It is basically the same as a dictionary, but with this structure the value is also your key. You would create a hashset like this:
Dim cadParts As New Hashset(Of String)
I won't go through code examples because it is very close to the Dictionary. ContainsKey becomes Contains, and Add accepts only one argument (which would be your part number here).
3) Yes, loop through them and add them to the hashset.
If part number is unique (it is not repeated in the values you want to search for) then you can use sorted dictionary. Then remove the duplicates and use remaining items.
To compare you can use part number as follows:
if(dictionary.ContainsKey(partNumber))
dictionary.Remove(partNumber)
end if
Given that there will only be a certain number of rows of the data grid visible at one time, it might be quicker to implement some code in the OnPaint method (I'm a little rusty here so apologies if that isn't exactly right) for each of the rows which checks against the array of part information and sets the background color of each row as it becomes visible, perhaps even marking each row as having been processed so the operation doesn't need to be repeated. There might be an initial performance gain here over processing all of the rows at once.
Of no real relevance; but from previous experience this sounds like you are interfacing with AutoDESK Inventor files?
Another solution could be to implement the IComparable(Of T) interface
That would require for you to build a class that you would use for both situation.
Public Class Item
Implements IComparable(Of Item)
Private _Description As String
Public Property Description() As String
Get
Return _Description
End Get
Set(ByVal value As String)
_Description = value
End Set
End Property
Private _PartNo As Integer
Public Property PartNo() As Integer
Get
Return _PartNo
End Get
Set(ByVal value As Integer)
_PartNo = value
End Set
End Property
Public Function CompareTo(ByVal other As Item) As Integer Implements System.IComparable(Of Item).CompareTo
' Your rules for comparing content for objects
If other.PartNo <> Me.PartNo Then Return 1
If other.Description <> Me.Description Then Return 1
' Return 0 if the object are the same
Return 0
End Function
End Class
Here is a small test that works with upper implementation.
Dim item As New Item
item.Description = "Desc"
item.PartNo = 34
Dim item2 As New Item
item2.Description = "Desc"
item2.PartNo = 35
Dim item3 As New Item
item3.Description = "Desc"
item3.PartNo = 36
Dim listFromDatabase As New Generic.List(Of Item)
listFromDatabase.Add(item)
listFromDatabase.Add(item2)
If listFromDatabase.Contains(item2) Then
MessageBox.Show("item2 was found in list")
End If
If Not listFromDatabase.Contains(item3) Then
MessageBox.Show("item3 was NOT found in list")
End If
Hope it helps a bit,
- Dan