Being new to programming and having it introduced to me through my course I've been doing tasks in and out of College in Visual Basic using Visual Studio to make games and other little applications. However in my most recent project i've experienced a problem in one of my arrays I have never come across before. The specific error im getting comes up with this when highlighted:
Data type(s) of the type parameter(s) in method 'Public Shared Overloads Function IndexOf(Of T)(array As T(), value As T) As Integer' cannot be inferred from these arguments. Specifying the data type(s) explicitly might correct this error.
I have all the arrays (18, for 9 different buttons each containing a question and an answer variant) running in form load as it was the only way I could get the arrays to work with a randomiser and show the question in the button. Then the array index is being found and created in the submit answer button. I'll give some snippets for further context below from various points where the array is being referenced :)
I created this to make the string global but I have an inkling this is wrong?
Public Class Form3
Public QBox1 As String
Public QBoxA1 As String
This is where the arrays are and how i've structured them
Public Sub Form3_Load(sender As Object, e As EventArgs) Handles MyBase.Load
BOX 1 (TOP LEFT)
Dim QBox1() As String = {"√81", "4x6", "16/4", "21+18", "81-23"}
Dim QBoxA1() As Integer = {"9", "24", "4", "39", "58"}
And finally this is within the submit answer button where the error is
If QBoxA1.Contains(txt_AnswerAttempt.Text) Then
Dim question_index = Array.IndexOf(QBox1, btn_Q1.Text)
Dim answer_index = Array.IndexOf(QBoxA1, answerAttemptDisplay.Text)
If question_index = answer_index Then
MsgBox("Correct Answer!")
Else
MsgBox("Wrong Answer!")
End If
End If
Sorry for information overload, I wanted to be thorough right off the bat! Cheers for giving this a read if you made it to the end xD
Your declaration isn't right. Since you want an array, don't declare it as a single string. It should be:
Public QBox1() As String
then in the load event, don't re-declare it with a Dim statement. Just re-populate it:
QBox1 = {"√81", "4x6", "16/4", "21+18", "81-23"}
Related
I've been thoroughly combing StackOverflow and other sources for the answers to these problems, and have not been able to find a solution that would work cohesively with the steps I need to accomplish.
Things I need to do:
Create an array from a text file and display in a listbox (this is done and works)
Have user fill in a text box, click a button, and the array is searched for anything matching the text box's value
Have the results of the search displayed in a separate listbox
Here's what I've got so far, and it's fairly hacked together, so if there's anything that can be improved, naturally, I'd be all for that.
`
Public Class Form1
Dim lblName As Object
Public colleges As String
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
Dim colleges() As String = IO.File.ReadAllLines("Colleges.txt")
ListBoxCollege.Items.AddRange(colleges)
End Sub
Private Sub btnSearchGo_Click(sender As Object, e As EventArgs) Handles btnSearchGo.Click
Dim n As Integer, college As String
college = txtCollegeSearchUserInput.Text
n = Array.IndexOf(colleges(), college)
If n <> 1 Then
[[Needs to output into new listbox, preferably here]]
End If
End Sub
If there's anything else needed from VB, I can provide if necessary!
In your case you can do something like this
For i As Integer = 0 To ListBoxCollege.Items.Count -1
If ListBoxCollege.Items(i).ToString().IndexOf(college, StringComparison.OrdinalIgnoreCase) > -1 Then
findList.Items.Add(ListBoxCollege.Items(i))
End If
Next
The difference here - you calling IndexOf on array and I call it for each item in list. Therefore I return all matches, while you only the first one
This is little bit limited in search criteria. You could use regex as well for wild cards etc. Or you store your data (colleges) in System.Data.DataTable, and you would be able to run Sql Select queries on it almost like in database.
I have built a workflow designer that allows to enter a list of email addresses.Each email in the list needs to be an InArgument(Of String) so they can be individually edited/added using variables.
On my Activity, I have a property that is declared like so:
Public Property [To] As ObservableCollection(Of InArgument(Of String))
My designer is wired up and populating this collection properly.
However during the execution, I do not know how to get the run-time value for each InArgument that was added.
When we are executing the workflow and iterating for each InArgument added to the list, I attempted to get the value as shown below but that fails:
For Each toAddress As InArgument(Of String) In Me.To.ToList()
Dim emailToAddress As String = toAddress.Get(_Context)
Next
The error we get is “The argument of type '<type>' cannot be used. Make sure that it is declared on an activity” and type is a string in my case...
The error we get sort of make sense because we haven’t declared a property on the activity since it was added dynamically to the list and therefore cannot get the value using the syntax shown below:
The_Property_Name.Get(_Context)
Can someone help? I can't seem to find anything. Should I be doing a different approach?
I figured it out so I will answer my own question! All we need to do is explicitly add the collection items to the metadata by overriding CacheMetadata() method on the activity. This then makes it available to the workflow context.
First we add them to the context:
Protected Overrides Sub CacheMetadata(ByVal metadata As CodeActivityMetadata)
MyBase.CacheMetadata(metadata)
Dim i As Integer = 0
For Each item As InArgument(Of String) In Me.To
Dim runTimeArg As RuntimeArgument = New RuntimeArgument("TO" & i.ToString(), item.ArgumentType, item.Direction, False)
metadata.Bind(item, runTimeArg)
metadata.AddArgument(runTimeArg)
i = i + 1
Next
End Sub
Then when executing, we get the values like this
For Each item As InArgument(Of String) In Me.To
Dim email As String = _Context.GetValue(item)
Next
I followed an example on stackoverflow about how to read database records into variables. This is the first time doing this and I feel that I'm close but I'm baffled at this point about the problem.
Here is the link I am referring to:
Visual Basic 2010 DataSet
My code is shown below.
Public Class Form1
' DataSet/DataTable variables
Dim testdataDataSet As New DataSet
Dim dttestdataDataTable As New DataTable
Dim datestdataDataAdapter As New Odbc.OdbcDataAdapter
' Variables for retrieved data
' Dim sSpeed As String = ""
' Dim sFuelprice As String = ""
Dim sSpeed As Integer
Dim sFuelprice As Integer
'Connect to the database
''
'Fill DataSet and assign to DataTable
datestdataDataAdapter.Fill(TestdataDataSet , "TestdataDataSet")
dttestdataDataTable = TestdataDataSet.Tables(0)
'Extract data from DataTable
' Rows is the row of the datatable, item is the column
sSpeed = dtTestdataDataTable.Rows(0).Item(0).ToString
sFuelprice = dtTestdataDataTable.Rows(0).Item(1).ToString
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
result.Text = Val(miles.Text) * sSpeed * sFuelprice
End Sub
End Class
Basically, I am getting declaration errors and I don't understand why since the example I was following clearly declared them. I'm connecting to an Access DB called "testdata.mdb" which contains only 1 record with two fields that I want to use throughout the program. The exanple said to dim the variables for each field as strings but this created more dim errors so I made them into integers and remarked out the original dim statements in the meantime (since they're going to be used in calculations.) The dataadapter and datatable variables also are getting flagged for not being declared when they were earlier in the program. I know this must be a simple thing to fix but I'm just not seeing it.
The form is just a simple thing where the user types in a number and a result is produced by using the numbers read in from the database. In short, I want to be able to do simple calculations with a database within a program and the dim statement thing is getting in the way.
If someone can please clarify what I should do, that would be very much appreciated. Thanks!
When you're trying to learn new technology, it's usually best to work from the outside in. The "outside-most" object in your case seems to be an OdbcConnection object.
Public Class Form1
Const connectionString as String = "Driver={Microsoft Access Driver (*.mdb)};DBQ=c:\bin\Northwind.mdb"
Dim connection As New OdbcConnection(connectionString)
connection.Open()
connection.Close()
end Class
Resolve errors at that level first. Then add a declaration for the data adapter--only for the data adapter--and resolve any errors with that. Repeat until you finish your class.
See OdbcConnectionString, and refer to the connection string web site if you need to.
I apologize for the delay in writing the answer to close off this question and sum it up.
In my case, it dataset is a one row database called testdata and contains 20 fields.
The solution that worked is as follows:
Immediately after the form1_load event, the variables can be immediately written after the dataadapter line:
Me.TestdataTableAdapter.Fill(Me.fooDataSet.testdata)
speed = Me.fooDataSet.testdata(0).speed
fuelprice = Me.fooDataSet.testdata(0).fuelprice
mpg = Me.fooDataSet.testdata(0).mpg
Then just DIM the variables to whatever you want them to be (in this case, speed is an integer, fuelprice is a decimal and MPG is a decimal) right after the PUBLIC CLASS statement at the top of your form's code.
You can then manipulate the variables in calculations after a button click as such:
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
fuelcost = CDec((miles.Text/ mpg) * fuelprice)
txtfuelcost.Text = fuelcost.ToString
End Sub
Thank you all for your responses!
I am very new to VBS, but I am not able to implement even the simplest things, as it seems. I want to have a class which holds an array in a private member. Since I want to "inject" the array I tried to implement a "setter-method" using the Let functionality.
Class CPhase
Private m_AllowedTasks()
Public Property Let AllowedTasks(p_AllowedTasks)
m_AllowedTasks = p_AllowedTasks
End Property
Private Sub Class_Initialize()
ReDim m_AllowedTasks(0)
End Sub
End Class
This class is used as follows:
Dim allowed
allowed = Array("task1", "task2")
Dim phase
Set phase = New CPhase
phase.AllowedTasks = allowed
This results in a "Microsoft VBScript runtime error (...) : Type mismatch" in the Let-method. I also tried using different combinations of "ByVal", "ByRef", but since having absolutely no experience with VBS I couldn't find a solution. So what am I doing wrong?
Any hints or links to helpful ressources are very appreciated!
Thanks!
The culprit is
Private m_AllowedTasks()
which creates an abomination - a fixed array of no size. Just remove the ().
Private m_AllowedTasks
to create an (empty) Variant that may be set=let to an useful (redim-able) array.
Its been a while since I've worked with ASP, but I'm getting a Type mismatch error on what seems to be a simple assignment statement. Can anyone shed some light on why this might be happening.
This works, but when I try to foreach an unassigned Questions block I get an Object not a collection error
Class Survey
public ID
public Title
public Questions
End Class
Sub Test()
Dim oSurvey
Set oSurvey = new Survey
Dim aQuestions(2)
Set aQuestions(0) = new Question
' Other aQuestions assignments
oSurvey.Questions = aQuestions
End Sub
Alternately If I setup questions as a dynamic array then the assignment fails with a type mismatch error.
Class Survey
public ID
public Title
public Questions()
End Class
Sub Test()
Dim oSurvey
Set oSurvey = new Survey
Dim aQuestions(2)
Set aQuestions(0) = new Question
' Other aQuestions assignments
' Throws a Type mismatch error here
oSurvey.Questions = aQuestions
End Sub
Any thoughts?
To answer your question as to what is actually going on.
when I try to foreach an unassigned
Questions block I get an Object not a
collection error
For Each enumerates a set of variants from the source variable, it does this by acquiring an IEnumVARIANT. If the source variable holds an object it is expected to have an implementation of this interface. If it is an array VBScript creates an implementation dynamically and it can only do this if the array has been dimensioned. Anything else in the source variable (such as Empty in this case) will result in an error.
then the assignment fails with a type mismatch error.
The left hand side of an assignment operation must always be a variant. Hence its not possible copy the contents of one dynamic array to another via a simple assignment.
Your first approach is reasonably sound but you need a way to represent an empty array without crashing out a For Each. You can use this little trick:-
Function EmptyArray
EmptyArray = Split("", " ")
End Function
Class Survey
public ID
public Title
public Questions
Private Sub Class_Initialize
Questions = EmptyArray
End Sub
End Class
Now if you try to For Each the Questions before it has been assigned a real array the for each will do nothing as expected. Also if you use UBound(Questions) + 1 to get the count of questions that will still be accurate since UBound(EmptyArray) is -1.
If I try to paste the same code into VBA (excel or word), it doesn't compile.
It shows error on line public Questions() saying
---------------------------
Microsoft Visual Basic
---------------------------
Compile error:
Constants, fixed-length strings, arrays, user-defined types and Declare statements not allowed as Public members of object modules
---------------------------
OK Help
---------------------------
In the first example, you haven't defined it as an array (it is a variant & hence can be assigned any value).
Update: I tested this in ASP.NET not realizing the question was about classic ASP. I've modified the code below to work with classic ASP, though I haven't been able to test it yet:
Class Question
...
End Class
Class Survey
Public ID
Public Title
Public Questions As Question()
End Class
Sub Test()
Dim oSurvey As New Survey
Dim aQuestions(0 To 2) As Question
Set aQuestions(0) = New Question
...
Set oSurvey.Questions = aQuestions
End Sub
In your first example, Survey.Questions isn't a collection; in your second, it is an array of Type Variant.
So I ended up sticking with the Array declaration. Additionally, When I tried to ReDim the array like so I got an error.
ReDim oSurvey.Questions(2)
So I created a sub routine to ReDim the Array, and this worked.
Class Survey
public ID
public Title
public Questions()
sub ReDimQuestions(count)
ReDim Questions(count)
end sub
End Class
Sub Test()
Dim oSurvey
Set oSurvey = new Survey
oSurvey.ReDimQuestions 2
Set oSurvey.Questions(0) = new Question
' Other aQuestions assignments
End Sub