I'm trying to make a calendar in vb.net and I have come across this problem. I want to append some text into an existing datatable row. When I watch my debugger it says:"In order to evaluate an indexed property, the property must be qualified and the arguments must be explicitly supplied by the user.".
Dim aantalRijen As Integer = 1
For x = 0 To 6
Dim dttopdrachten As New DataTable
dttopdrachten = opdrachtendao.getOpdrachtenByDate(Today.AddDays(x))
If dttopdrachten.Rows.Count > aantalRijen Then
aantalRijen = dttopdrachten.Rows.Count
End If
Next
For z = 0 To aantalRijen - 1
Dim r As DataRow
r = dttAgenda.NewRow()
dttAgenda.Rows.InsertAt(r, z)
Next
For i = 0 To 6
Dim aantalItems As Integer = 0
Dim dttopdrachten As New DataTable
dttopdrachten = opdrachtendao.getOpdrachtenByDate(Today.AddDays(i))
aantalItems = dttopdrachten.Rows.Count
For j = 0 To aantalItems - 1
Dim info As String = dttopdrachten.Rows(j).Item(0).ToString & vbCrLf & dttopdrachten.Rows(j).Item(2).ToString & vbCrLf & dttopdrachten.Rows(j).Item(3).ToString & vbCrLf & dttopdrachten.Rows(j).Item(4).ToString & vbCrLf & dttopdrachten.Rows(j).Item(5).ToString & vbCrLf & dttopdrachten.Rows(j).Item(6).ToString
dttAgenda.Rows(j).Item(i) = info
Next
Next
dgvAgenda.DataSource = dttAgenda
In the code above, I first count how many rows I have to make. Afterwards I add the amount of rows to the datatable (columns are added before). Until here it works, but then when I keep debugging I get the error. I tried googling but nothing could help me so far.
Seem problem has been solved without changing anything. So if someone want to make a calendar. Here's the solution ;)
Related
I have a dataset that contains multiple values. I want to take those rows from that dataset that contains "the specific value" and firstly I want to display those in a MessageBox.
Furtheron, I try to view them in a datagridview called ErrorsDgV.
I already searched this topic and found a good function, but unfortunately, all I get from the MessageBox is an empty box.
ErrorsDgV.DataSource = Srchdataset.Tables("blubb")
LineLabel.Text = "Lines: " &
Srchdataset.Tables("blubb").Rows.Count.ToString
ErrorsDgV.Sort(ErrorsDgV.Columns(1), System.ComponentModel.ListSortDirection.Ascending)
ErrorsDgV.AutoSizeColumnsMode = DataGridViewAutoSizeColumnsMode.AllCells
ErrorsDgV.Columns(1).DefaultCellStyle.Format = "dd/MM/yyyy HH:mm:ss.fff"
Dim answer As String = ""
Dim SearchRows() As Data.DataRow
SearchRows = Srchdataset.Tables("blubb").Select("Data = 'the specific value'")
answer = ""
For k As Integer = 0 To SearchRows.Length - 1
If answer = "" Then
answer = SearchRows(k).Item("Data")
Else
answer = answer & vbNewLine & SearchRows(k).Item("Data")
End If
Next
MsgBox(" " & answer)
I debugged also and got to know that SearchRows is empty, even if the specific value is inlcuded in that DataSet.
I don't know a lot about the subject of sorting but here goes: I am trying to sort a music library (comma seperated in a csv file. Some examples):
1,Sweet Home Alabame,Lynyrd Skynyrd,4:40,Classic Rock
2,Misirlou,Dick Dale,2:16,Surf Rock
I need to sort them alphabetically (by title of track) but I don't know two things: 1. Why my current technique isn't working:
Dim array() As String = {}
sr = New StreamReader("library.csv")
counter = 1
Do Until sr.EndOfStream
array(counter) = sr.ReadLine()
counter += 1
Loop
System.Array.Sort(Of String)(array)
Dim value As String
For Each value In array
Console.WriteLine(value)
Next
Console.ReadLine()
I don't know if this is the best way of sorting. I then need to display them as well. I can do this without sorting, but can't figure out how to do it with sorting.
Help please (from people who, unlike me, know what they're doing).
Right now you're putting all fields in one long string of text (each row).
In order to sort by a particular field, you'll need to build a matrix of rows and columns. For example, a DataTable.
Here's a class that should do the trick for you:
https://www.codeproject.com/Articles/11698/A-Portable-and-Efficient-Generic-Parser-for-Flat-F
Here's the sample usage code from the article, translated to VB:
Public Class CsvImporter
Public Sub Import()
Dim dsResult As DataSet
' Using an XML Config file.
Using parser As New GenericParserAdapter("MyData.txt")
parser.Load("MyData.xml")
dsResult = parser.GetDataSet()
End Using
' Or... programmatically setting up the parser for TSV.
Dim strID As String, strName As String, strStatus As String
Using parser As New GenericParser()
parser.SetDataSource("MyData.txt")
parser.ColumnDelimiter = vbTab.ToCharArray()
parser.FirstRowHasHeader = True
parser.SkipStartingDataRows = 10
parser.MaxBufferSize = 4096
parser.MaxRows = 500
parser.TextQualifier = """"c
While parser.Read()
strID = parser("ID")
strName = parser("Name")
' Your code here ...
strStatus = parser("Status")
End While
End Using
' Or... programmatically setting up the parser for Fixed-width.
Using parser As New GenericParser()
parser.SetDataSource("MyData.txt")
parser.ColumnWidths = New Integer(3) {10, 10, 10, 10}
parser.SkipStartingDataRows = 10
parser.MaxRows = 500
While parser.Read()
strID = parser("ID")
strName = parser("Name")
' Your code here ...
strStatus = parser("Status")
End While
End Using
End Sub
End Class
There's also this from here, demonstrating DataTable usage:
Dim csv = "Name, Age" & vbCr & vbLf & "Ronnie, 30" & vbCr & vbLf & "Mark, 40" & vbCr & vbLf & "Ace, 50"
Dim reader As TextReader = New StringReader(csv)
Dim table = New DataTable()
Using it = reader.ReadCsvWithHeader().GetEnumerator()
If Not it.MoveNext() Then
Return
End If
For Each k As var In it.Current.Keys
table.Columns.Add(k)
Next
Do
Dim row = table.NewRow()
For Each k As var In it.Current.Keys
row(k) = it.Current(k)
Next
table.Rows.Add(row)
Loop While it.MoveNext()
End Using
And this Q&A illustrates how to sort the DataTable by a given column.
I'm learning for loop and I cannot get this problem fixed.
The problems are in the following codes.
dim rt as integer = 2
dim i As Integer = 0
dim currentpg as string = "http://homepg.com/"
For i = 0 To rt
currentpg = currentpg & "?pg=" & i
messagebox.show(currentpg)
next
'I hoped to get the following results
http://homepg.com/?pg=0
http://homepg.com/?pg=1
http://homepg.com/?pg=2
'but instead I'm getting this
http://homepg.com/?pg=0
http://homepg.com/?pg=0?pg=0
http://homepg.com/?pg=0?pg=0?pg=0
Please help me
Thank you.
You probably need something like this:
Dim basepg as string = "http://homepg.com/"
For i = 0 To rt
Dim currentpg As String = basepg & "?pg=" & i
messagebox.show(currentpg)
Next
Although a proper approach would be to accumulate results into a List(Of String), and then display in a messagebox once (or a textbox/file, if too many results). You don't want to bug user for every URL (what if there are 100 of them?). They would get tired of clicking OK.
First of all, you went wrong while copying the output of the buggy code. Here is the real one.
http://homepg.com/?pg=0
http://homepg.com/?pg=0?pg=1
http://homepg.com/?pg=0?pg=1?pg=2
It does not work because currentpg should be a constant but it is changed on each iteration.
Do not set, just get.
MessageBox.Show(currentpg & "?pg=" & i)
Or you can use another variable to make it more readable.
Dim newpg As String = currentpg & "?pg=" & i
MessageBox.Show(newpg)
Also, your code is inefficient. I suggest you to change it like this.
Dim iterations As Integer = 2
Dim prefix As String = "http://homepg.com/?pg="
For index As Integer = 0 To iterations
MessageBox.Show(prefix & index)
Next
Dim ssi(11) As String
For i = 0 To 10
If ssi(i) = "" Then ssi(i) = "0"
For j = 0 To Val(ssi(11)) + i
ssi(i) = xuh(Val(ssi(i)))
Next
Next
If ssi(11) = "2" Then
L_zz.Caption = Val(Left(ssi(0) & ssi(1) & ssi(2) & ssi(3) & ssi(4) & ssi(5) & ssi(6) & ssi(7), ssi(10)))
ElseIf ssi(11) = "3" Then
L_zz.Caption = Val(Left(ssi(0) & ssi(1) & ssi(2) & ssi(3) & ssi(4) & ssi(5) & ssi(6) & ssi(7), ssi(10))) * (-1)
End If
I am new here and new to VB as well.
I am trying to understand this double loop in vb code.
ssi(i) is defined as a String variable. and each element is assigned to a specific number in a String. Hope I told it clearly.
My problem with this loop is below.
Since i ranges from 0 to 10, what does this j mean? Does j mean the new ssi(1-10) or another whatever number?
I think the best way to answer your question about understanding a double loop is to try looking at something simpler.
The first program I always write in each new version of BASIC that comes along is a 12 times table.
I've modified it a bit below to be a 12 x 10 table for the purpose of illustrating for you how a double loop works ... hope it helps:
For x As Integer = 1 To 12
For y As Integer = 1 To 10
Console.Write(x * y)
Console.Write(vbTab)
Next
Console.WriteLine()
Next
I am trying to perform a SQL Select query based on the user input from a Checked List Box. I was able to find some code, but the solution doesn't seem to be working. On the debug, it keeps crapping out on line 3 and I have no idea why.
Any help would be grateful.
Dim DistrictString As StringBuilder = New StringBuilder()
For h = 0 To Me.District.CheckedItems.Count - 1
If Me.District.CheckedItems(h).Selected Then
DistrictString.Append(Me.District.CheckedItems(h).Value & ",")
End If
Next
With some of the advice, here is the newly edited version of the code, it is now crashing on the Append line.
The new error is 'Public member 'Value' on type 'String' not found'
Dim DistrictW As String
Dim DistrictX As String
Dim DistrictString As StringBuilder = New StringBuilder
For h = 0 To Me.District.CheckedItems.Count - 1
DistrictString.Append(Me.District.CheckedItems(h).Value & ",")
Next
DistrictW = DistrictString.ToString
DistrictX = DistrictW.Substring(0, DistrictString.Length - 1)
If Me.District.CheckedItems.Items(h).Selected Then
DistrictString.Append(Me.District.CheckedItems.Items(h).Value & ",")
End If
Use CheckboxList.Items
Thank you to everyone who helped, this is the solution that I implemented
Learned a lot from this little exercise.
Dim DistrictW As String
Dim DistrictX As String
Dim DistrictString As StringBuilder = New StringBuilder
For h = 0 To Me.District.CheckedItems.Count - 1
DistrictString.Append(Me.District.CheckedItems(h).ToString & ",")
Next
DistrictW = DistrictString.ToString
DistrictX = DistrictW.Substring(0, DistrictString.Length - 1)
Since it appears you are creating a expression like ...xyz in ('a', 'b', 'c', 'd')... the following code might be more appropriate:
For h = 0 To Me.District.CheckedItems.Count - 1
DistrictString += "'" & Me.District.CheckedItems(h).Value & "',"
Next
DistrictString = DistrictString.Substring(0, DistrictString.Length - 1)
There is no point in messing with the .SELECTED property at all. Everything that's checked is 'selected' for your purposes.