I want to get value from datatable and then store it to the string() arraylist. datatable contain 3 column (columnA | columnB | columnC). I want to get all value from columnB and store it to arraylist.
I have try something like this
If myTableData.Rows.Count > 0 Then
For i As Integer = 0 To myTableData.Rows.Count - 1
Dim value() As String = myTableData.Rows(i)(1)
Next
End If
but when I compile that code, I got error message like this :
Unable to cast object of type 'System.String' to type 'System.String[]'
please help me.....
You could do that with LINQ:
Dim colBValues = (From row In myTableData Select colB = row(1).ToString).ToList
Or if you prefer the "old-school" way:
Dim colBValues = New List(Of String)
For Each row As DataRow In myTableData.Rows
colBValues.Add(row(1).ToString)
Next
I've used a List(Of String) because it's type-safe, therefore you don't need to cast the values everytime. That makes code more readable, more failsafe and faster.
If you need it as String-Array, you could simply use ToArray:
Dim colBValues = (From row In myTableData Select colB = row(1).ToString).ToArray
List(T)
LINQ
Dim a() As String
Dim total As Integer
'Count the number of rows
total = myTableData.Rows.Count - 1
ReDim a(0 To total)
For i = 0 To total
a(i) = myTableData.Rows(i)(1)
Next
This is really old question, but I'll provide one more variant of answer :
Dim value = myTableData.Rows.OfType(Of DataRow).Select(Function(x) x(1).ToString()).ToArray
So, if You have more than one column in Your DataTable You can use x(columnIndex) instead 1.
Related
I have got a problem, I have got a filled dataset, but now i need to get a Column value from it and store it into a variable. On Button 2 click i fill it with this:
tbaGridview.Fill(BlGridview1.vwBLcontainerCargo, Bookingnumber)
Now i want to get the data from it that is inside. I have got a for loop:
For i As Integer = 0 To GridView1.DataRowCount - 1
Dim OriginSealNumber As String = BlGridview1.vwBLcontainerCargo.Tables("SEALNUMBER").Rows(i).Item(0)
Next i
But it says Tables is not a member of windowsapplication1.blgridView.vwBLContainerCargoDataTable. How do i get the data for each column??
To reference the GridView's table use this sintax:
((DataRowView)GridView1.Rows[0].DataBoundItem).DataView.Table
But I recommend that you use a BindingSource object and iterate through it.
I fixed it myself by using this:
For i As Integer = 0 To GridView1.DataRowCount - 1
Dim OriginSealNumber As String = BlGridview1.Tables(0).Rows(i)("SEALNUMBER").ToString()
Dim OriginContainerNumber As String = BlGridview1.Tables(0).Rows(i)("CONTAINERNUMBER").ToString()
Dim OriginContainerType As String = BlGridview1.Tables(0).Rows(i)("CONTAINERTYPE").ToString()
Dim OriginQuantity As String = BlGridview1.Tables(0).Rows(i)("QUANTITY").ToString()
Dim OriginPackageType As String = BlGridview1.Tables(0).Rows(i)("PACKAGETYPE").ToString()
Dim OriginDescription As String = BlGridview1.Tables(0).Rows(i)("DESCRIPTION").ToString()
Dim OriginWeight As String = BlGridview1.Tables(0).Rows(i)("WEIGHT").ToString()
Next i
I have this problem in vb.net. Lets say I got 2 Lists ListA and ListB both holds objects of same type.
Eg., one of the property of the object is ID. (ID is written in brackets)
ListA ListB
---------------------------
A(3818) A(3818)
B(3819) B(3819)
C(3820) C(3820)
D(3821) D(3821)
E(3823) F(0)
H(3824) G(0)
I(3825)
How do I merge these two Lists to have a new distinct list which holds objects only once whose ID matches and all other objects(whose ID dont match) are simply added to the new list.
Sample output be,
New List
--------
A(3818)
B(3819)
C(3820)
D(3821)
E(3823)
F(0)
G(0)
H(3824)
I(3825)
When I searched I found that AddRange() and Union are some of the methods to do the merge. But i am not able to find if this works for non standard objects(apart from Integer, String)
Use addRange() and then linq with distinct to filter out the duplicates.
Dim b = YourCollection.Distinct().ToList()
Could use a collection bucket
Dim oCol As New Collection
AddTitems(oCol, oListA)
AddTitems(oCol, olistB)
Public Function AddTitems(oSummaryList As Collection, oList As List(Of thing)) As Collection
For Each oThing As thing In oList
If Not oSummaryList.Contains(CStr(oThing.ID)) Then oSummaryList.Add(oList, CStr(oThing.ID))
Next
Return oSummaryList
End Function
Here are a couple simple functions that should do that for you. I'm not sure how efficient they are though. I don't think there is anything built in.
Private Function nameOfFunction(list1 as list(of type), list2 as list(of type)) as list(of type)
Dim result as new list(of type)
for a as integer = 0 to math.max(list1.count, list2.count) - 1 step 1
If a < list1.count AndAlso resultHasID(result, list1(a).ID) = False Then
result.add(list1(a))
end if
If a < list2.count AndAlso resultHasID(result, list2(a).ID) = False Then
result.add(list2(a))
end if
next
End Function
Private Function resultHasID(testList as list(of type), s as string) as boolean
Dim result as Boolean = False
for a as integer = 0 to testlist.count - 1 step 1
if(testlist(a).ID = s) then
result = true
exit for
End if
Next
Return result
End function
For each item as String in ListA
If Not ListB.Contains(item) Then
ListB.Add(item)
End If
Next
I have a DataTable dtand need to store the first n items of a certain column in an integer array. I know it's easy to do this with a loop like this:
Dim array(n-1) As Integer
For i As Integer = 0 To n-1
array(i) = dt.Rows(i).Item("columName")
Next
Nonetheless, is there a more convenient way to store these items in the array?
"Without using a loop" is impossible since there is no magic way to retrieve items from a collection without looping it. However, maybe you think that LINQ does not use loops:
Dim columNameValues = From row In dt
Select row.Field(Of Int32)("columName")
Dim array As Int32() = columNameValues.ToArray()
Gets all values from all rows, if you want to get n values use Enumerable.Take:
Dim array As Int32() = columNameValues.Take(n).ToArray()
In VB.NET you can even use Take in a LINQ query:
Dim first10Values = From row In dt
Select row.Field(Of Int32)("columName")
Take 10
For what it's worth, as Barry has mentioned it is technically possible to get n items from a collection without using a loop, but see yourself:
Dim value1 As Int32 = dt.Rows(0).Field(Of Int32)("columName")
Dim value2 As Int32 = dt.Rows(1).Field(Of Int32)("columName")
Dim value3 As Int32 = dt.Rows(2).Field(Of Int32)("columName")
' ..... '
Dim value10 As Int32 = dt.Rows(9).Field(Of Int32)("columName")
You could add them to a List(Of Int32), but that's just for demonstration purposes anyway.
i have a database in one field like below 222-225. I try to make split to read that value for my function. Just simple function a=225 b=222 then total=(a-b)+1. here my code
Dgv.CellClick
'Dim x As Boolean
Dim a As Double
Dim total As Double
a = CDbl(Dgv.Item(8, Dgv.CurrentRow.Index).Value)
Split(a, "-")
total = (a) - (a)
Dgv.Item(9, Dgv.CurrentRow.Index).Value = total
My problem is this doesn't work. I can't get the value that I split. Any idea how to solve this problem?
note: I use VB.NET 2005
If you want total=(a-b)+1 .. That should be
dim b = a.Split("-")
total = val(b(1)) - val(b(2)) + 1
may be this can help. try this...
Dim a As String
a = ""
Dim x As String
Dim total As Double
a = Dgv.Item(8, Dgv.CurrentRow.Index).Value.ToString
Dim ary() As String
x = a
ary = x.Split("-")
total = CInt(ary(1)) - CInt(ary(0))
Dgv.Item(9, Dgv.CurrentRow.Index).Value = total
Like others have said, Split() returns a String array, like this:
Dim SplitValue() As String = Split(a, "-")
total = (CType(SplitValue(1), Double) - CType(SplitValue(0), Double)) + 1
If I read your question correctly, the value you're looking for is 222-225, and that value is located in the specified cell of Dgv (which I'm guessing is a DataGridView). If my understanding is correct, there are a couple of things going on.
First, I'm not sure why you're trying to convert that value to a double with the following line of code:
a = CDbl(Dgv.Item(8, Dgv.CurrentRow.Index).Value)
The Item property of a DataGridView holds a DataGridViewCell, and the Value property of the DataGridViewCell returns an Object. Trying to convert 222-225 to a double will, I believe, fail (though since this is VB.NET, it's possible it won't depending on the options you set - I'm not as familiar with VB.NET as I am with C#).
Even if it does successfully work (I'm not sure what the output would be), Split expects a string. I would change that line of code to the following:
a = Dgv.Item(8, Dgv.CurrentRow.Index).Value.ToString()
Now you have a string that you can use Split on. The Split you have in your posted code appears to be the Visual Basic (pre-.NET) Split method Split Function (Visual Basic). As others have mentioned, Split returns an array of strings based on the delimiter. In your code, you don't assign the result of Split to anything, so you have no way to get the values.
I would recommend using the .NET version of Split (String.Split Method) - there are several ways you can call String.Split, but for purposes of your code I'd use it like this:
Dim splits As String() = a.Split(New Char() { "-" })
Where a is the string value from the selected DataGridViewCell above. This will give you a 2-element array:
splits(0) = "222"
splits(1) = "225"
The final part is your formula. Since you have strings, you'll need to convert them to a numeric data type:
total = (CDbl(splits(1)) - CDbl(splits(0))) + 1
Which becomes (225 - 222) + 1 = 4.
Putting it altogether it would look something like this:
Dim a As String
Dim total As Double
Dim splits() As String
a = Dgv.Item(8, Dgv.CurrentRow.Index).Value.ToString()
splits = a.Split(New Char() { "-" })
total = (CDbl(splits(1)) - CDbl(splits(0))) + 1
Dgv.Item(9, Dgv.CurrentRow.Index).Value = total
Split returns an array. something like this. VB.Net is not my primary language but this should help.
dim arr = a.Split(New Char (){"-"})
total = ctype(arr(0), double) - ctype(arr(1),double)
Try this:
Dim aux() As String = a.Split("-"c)
total = CDbl(aux(0)) - CDbl(aux(1)) + 1
Dim a As string
Dim x As String
Dim total As Double
a = Dgv.Item(8, Dgv.CurrentRow.Index).Value
Dim ary() As String
x = a
ary() = x.Split("-")
total = CInt(ary(1)) - CInt(ary(0))
Dgv.Item(9, Dgv.CurrentRow.Index).Value = total
i have this code, and i want to access some variables.
Dim k1 as String = "Something"
Dim k2 as String = "Something"
... to k230
------------------Then i have this:
Dim rnd = New Random()
Dim nextValue = rnd.Next(230)
For i = 0 To 230
If nextValue = i Then
MsgBox('k+i') <--BUT READ THIS AS A VARIABLE.
End If
i = i + 1
Next
i readed some similar questions, but them doesn't apply to this case.
Consider using arrays here:
http://msdn.microsoft.com/en-us/library/vstudio/wak0wfyt.aspx
An array is a set of values that are logically related to each other,
such as the number of students in each grade in a grammar school.
By using an array, you can refer to these related values by the same
name, and use a number that’s called an index or subscript to tell
them apart. The individual values are called the elements of the
array. They’re contiguous from index 0 through the highest index
value.
Try using a Dictionary:
Dim k As New Dictionary(Of Integer, String)()
k.Add(1, "Something")
k.Add(2, "Something")
'... to 230
Messagebox.Show(k(i))