Visual Basic

Re: having problems with program to merge sort a given set of input

15-Oct-12 0:23

please i am having problems writing a program to merge sort using vb.net2010. here is my code any form of help will be appreciated.
i am also having problems outputing the sorted result into listbox2

Private Sub BTN_SORT_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles BTN_SORT.Click
    Dim arrayofinput()
    Dim low As Integer
    Dim high As Integer
    Dim length As Integer
    Dim middle As Integer
    Dim temp As Integer
    Dim m1 As Integer
    Dim m2 As Integer
    If low >= high Then Return
    Dim length As Integer = high - low + 1
    Dim middle As Integer = Math.Floor((low + high) / 2)
    Do(arrayofinput, low, middle)
        Do(arrayofinput.Length, middle + 1, high)
            Dim temp(arrayofinput.Length - 1) As Integer
            For i As Integer = 0 To length - 1
                temp(i) = arrayofinput(low + i)
            Next
            Dim m1 As Integer = 0
            Dim m2 As Integer = middle - low + 1
            For i As Integer = 0 To length - 1
                If m2 <= high - low Then
                    If m1 <= middle - low Then
                        If temp(m1) > temp(m2) Then
                            arrayofinput(i + low) = temp(m2)
                            m2 += 1
                        Else
                            arrayofinput(i + low) = temp(m1)
                            m1 += 1
                        End If
                    Else
                        arrayofinput(i + low) = temp(m2)
                        m2 += 1
                    End If
                Else
                    arrayofinput(i + low) = temp(m1)
                    m1 += 1
                End If
            Next
            ListBox2.Items.Add(ListBox1.Items.Add(input))
End Sub

Eddy Vluggen15-Oct-12 0:50

Re: having problems with program to merge sort a given set of input

15-Oct-12 0:50

benkazy1014 wrote:
please i am having problems writing a program to merge sort using vb.net2010. here is my code any form of help will be appreciated.

i am also having problems outputing the sorted result into listbox2

We'll need more description of the problem; does it generate an exception? If yes, what did the message say?

Does it compile? Does it run? If yes, upto where? Did it error at all, or does it just generate a different output than expected?

Bastard Programmer from Hell Suspicious | :suss:

if you can't read my code, try converting it here[^]

benkazy101415-Oct-12 1:36

Re: having problems with program to merge sort a given set of input

15-Oct-12 1:36

it does not compile

Eddy Vluggen15-Oct-12 2:16

Re: having problems with program to merge sort a given set of input

15-Oct-12 2:16

If it does not compile, you'll get a compiler-error. What does the error say?

Bastard Programmer from Hell Suspicious | :suss:

if you can't read my code, try converting it here[^]

benkazy101415-Oct-12 2:38

Re: having problems with program to merge sort a given set of input

15-Oct-12 2:38

Error 8 Variable temp, m1 and m2 hides a variable in an enclosing block.
do must end with a matchin loop.
temp is not an array,expression not a method
and a whole lot of errors . although it accepts inputs, it does not sort.have you ever tried anything on this topic? if yes how did you go about it. i am desperately in need of help. thank you.

Eddy Vluggen15-Oct-12 2:47

Re: having problems with program to merge sort a given set of input

15-Oct-12 2:47

benkazy1014 wrote:
Error 8 Variable temp, m1 and m2 hides a variable in an enclosing block.

That means that you already have a variable called "m1" (and another m2) outside of that loop; that gets very confusing when reading code. It's best to give them descriptive names. Can you paste the offending block here? Perhaps we can rewrite it a bit Smile | :)

--edit; you already posted the code, that's what got this whole thing started. My mistake, I'm doing some things simultaneous. To the code, and first error;

Private Sub BTN_SORT_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles BTN_SORT.Click
    Dim arrayofinput()
    Dim low As Integer
    Dim high As Integer
    Dim length As Integer
    Dim middle As Integer
    Dim temp As Integer
    Dim m1 As Integer ' You declare m1 here
    Dim m2 As Integer
    If low >= high Then Return
    Dim length As Integer = high - low + 1
    Dim middle As Integer = Math.Floor((low + high) / 2)
    Do(arrayofinput, low, middle)
        Do(arrayofinput.Length, middle + 1, high)
            Dim temp(arrayofinput.Length - 1) As Integer
            For i As Integer = 0 To length - 1
                temp(i) = arrayofinput(low + i)
            Next
            Dim m1 As Integer = 0 ' means you shouldn't declare it here anew.
                                  ' if it needs be zero here, just assign zero;
                                  ' m1 = 0
            Dim m2 As Integer = middle - low + 1 ' same here, a variable with this name 
                                                 ' already exists; use another name, or
                                                 ' assign the value without declaring a variable
            For i As Integer = 0 To length - 1
                If m2 <= high - low Then
                    If m1 <= middle - low Then
                        If temp(m1) > temp(m2) Then
                            arrayofinput(i + low) = temp(m2)
                            m2 += 1
                        Else
                            arrayofinput(i + low) = temp(m1)
                            m1 += 1
                        End If
                    Else
                        arrayofinput(i + low) = temp(m2)
                        m2 += 1
                    End If
                Else
                    arrayofinput(i + low) = temp(m1)
                    m1 += 1
                End If
            Next
            ListBox2.Items.Add(ListBox1.Items.Add(input))
End Sub

That's one. The second problem is that your loop does not conform the standard. If you insert a "do" statement, rules require a "loop" statement (see docs[^]). As it is now, the compiler will not recognize where your loop ends (despite the indentation).

Once you got those two fixed, we'll move to the rest Smile | :)

Bastard Programmer from Hell Suspicious | :suss:

if you can't read my code, try converting it here[^]

benkazy101415-Oct-12 1:38

Re: having problems with program to merge sort a given set of input

15-Oct-12 1:38

can you please help me with code in vb.net

Member 132474409-Jun-17 17:20

Member 13247440

9-Jun-17 17:20

you'll have to modify this code to suit your needs, but this is how I sort/merge text files.

m& = LBOUND(Master)
s& = LBOUND(Slave)
t& = 0
DO
    IF m& < MasterLines& THEN '* aka not eof(masterfile%)
        IF s& < SlaveLines& THEN '* aka not eof(slavefile%)
            IF Master(m&) > Slave(s&) THEN '* reached end of primary so flush secondary
                printToFile Slave(s&), OChannel%, s&, t&
            ELSE
                printToFile Master(m&), OChannel%, m&, t&
            END IF
        ELSE
            printToFile Master(m&), OChannel%, m&, t&
        END IF
    ELSE
        IF s& < SlaveLines& THEN
            printToFile Slave(s&), OChannel%, s&, t&
        ELSE
            EXIT DO
        END IF
    END IF
LOOP
CLOSE OChannel%
PRINT MasterLines& " lines merged from Master file "; Mast$
PRINT SlaveLines& " lines merged from Slave file "; Slav$
PRINT t& " Records written to "; OutPF$
DO
LOOP UNTIL INKEY$ > ""
SYSTEM

SUB printToFile (x$, channel%, RecsPrinted&, t&)
t& = t& +1 '* increment the appropriate array counter
RecsPrinted& = RecsPrinted& + 1 ' keep track of how many processed so far
PRINT #channel%, x$
END SUB


SUB MergeSort (array() AS STRING, start&, finish&)
IF start& < finish& THEN '* no need to do this for 0-sized sublists
    length& = finish& - start& + 1
    middle& = start& + (finish& - start&) \ 2
    MergeSort array(), start&, middle&
    MergeSort array(), middle& + 1, finish&
    REDIM temp(0 TO length& - 1) AS STRING
    FOR i& = 0 TO length& - 1
        temp(i&) = array(start& + i&)
    NEXT
    mptr& = 0
    sptr& = middle& - start& + 1
    FOR i& = 0 TO length& - 1
        IF sptr& > finish& - start& THEN
            array(i& + start&) = temp(mptr&)
            mptr& = mptr& + 1
        ELSE
            IF mptr& > middle& - start& THEN
                array(i& + start&) = temp(sptr&)
                sptr& = sptr& + 1
            ELSE
                IF temp(mptr&) > temp(sptr&) THEN
                    array(i& + start&) = temp(sptr&)
                    sptr& = sptr& + 1
                ELSE
                    array(i& + start&) = temp(mptr&)
                    mptr& = mptr& + 1
                END IF
            END IF
        END IF
    NEXT
    ERASE temp
END IF
END SUB

[SOLVED] How to update Gridview with value textbox = Null

zaimah14-Oct-12 22:25

Re: How to update Gridview with value textbox = Null

14-Oct-12 22:25

Hi, its been years i don't do vb. So its like im a junior in this. I have problem update my Gridview. My gridview is to update marks for student. The problem is, the update have problem if the textbox is with a NULL value. If i put 0 in the textbox, the update runs ok.

This is my gridview html

ASP.NET

<asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False" DataSourceID="SqlDataSource2">
            <Columns> 
                <asp:TemplateField HeaderText="Student ID" SortExpression="stID">
                    <ItemTemplate>
                        <asp:Label ID="Label11" runat="server" Width="50px" Text='<%# Bind("stID") %>'></asp:Label>
                    </ItemTemplate>
                </asp:TemplateField>
                <asp:TemplateField HeaderText="CO1" SortExpression="CO1">
                    <ItemTemplate>
                        <asp:TextBox ID="Label1" runat="server" Width="50px" Text='<%# Bind("CO1") %>'></asp:TextBox>
                    </ItemTemplate>
                </asp:TemplateField>
                <asp:TemplateField HeaderText="CO2" SortExpression="CO2">
                    <ItemTemplate>
                        <asp:TextBox ID="Label2" runat="server" Width="50px" Text='<%# Bind("CO2") %>'></asp:TextBox>
                    </ItemTemplate>
                </asp:TemplateField>
                <asp:TemplateField HeaderText="CO3" SortExpression="CO3">
                    <ItemTemplate>
                        <asp:TextBox ID="Label3" runat="server" Width="50px" Text='<%# Bind("CO3") %>'></asp:TextBox>
                    </ItemTemplate>
                </asp:TemplateField>
                <asp:TemplateField HeaderText="CO4" SortExpression="CO4">
                    <ItemTemplate>
                        <asp:TextBox ID="Label4" runat="server" Width="50px" Text='<%# Bind("CO4") %>'></asp:TextBox>
                    </ItemTemplate>
                </asp:TemplateField>
                <asp:TemplateField HeaderText="CO5" SortExpression="CO5">
                    <ItemTemplate>
                        <asp:TextBox ID="Label5" runat="server" Width="50px" Text='<%# Bind("CO5") %>'></asp:TextBox>
                    </ItemTemplate>
                </asp:TemplateField>
                <asp:TemplateField HeaderText="CO6" SortExpression="CO6">
                    <ItemTemplate>
                        <asp:TextBox ID="Label6" runat="server" Width="50px" Text='<%# Bind("CO6") %>'></asp:TextBox>
                    </ItemTemplate>
                </asp:TemplateField>
                <asp:TemplateField HeaderText="CO7" SortExpression="CO7">
                    <ItemTemplate>
                        <asp:TextBox ID="Label7" runat="server" Width="50px" Text='<%# Bind("CO7") %>'></asp:TextBox>
                    </ItemTemplate>
                </asp:TemplateField>
                <asp:TemplateField HeaderText="CO8" SortExpression="CO8">
                    <ItemTemplate>
                        <asp:TextBox ID="Label8" runat="server" Width="50px" Text='<%# Bind("CO8") %>'></asp:TextBox>
                    </ItemTemplate>
                </asp:TemplateField>
                <asp:TemplateField HeaderText="CO9" SortExpression="CO9">
                    <ItemTemplate>
                        <asp:TextBox ID="Label9" runat="server" Width="50px" Text='<%# Bind("CO9") %>'></asp:TextBox>
                    </ItemTemplate>
                </asp:TemplateField>
                <asp:TemplateField HeaderText="CO10" SortExpression="CO10">
                    <ItemTemplate>
                        <asp:TextBox ID="Label10" runat="server" Width="50px" Text='<%# Bind("CO10") %>'></asp:TextBox>
                    </ItemTemplate>
                </asp:TemplateField>
            </Columns>
             <RowStyle BackColor="White" ForeColor="#330099" />
            <FooterStyle BackColor="#FFFFCC" ForeColor="#330099" />
            <PagerStyle BackColor="#FFFFCC" ForeColor="#330099" HorizontalAlign="Center" />
            <SelectedRowStyle BackColor="#FFCC66" Font-Bold="True" ForeColor="#663399" />
            <HeaderStyle BorderColor="Maroon" BackColor="#990000" Font-Bold="True" ForeColor="#FFFFCC" />
        </asp:GridView>
        <asp:SqlDataSource ID="SqlDataSource2" runat="server" ConnectionString="<%$ ConnectionStrings:UTMConnectionString %>"
            SelectCommand="SELECT [stID], [CO1], [CO2], [CO3], [CO4], [CO5], [CO6], [CO7], [CO8], [CO9], [CO10] FROM [quiz] WHERE ([Cid] = @Cid)">
            <SelectParameters>
                <asp:SessionParameter Name="Cid" SessionField="CourseID" Type="String" />
            </SelectParameters>
        </asp:SqlDataSource>

The erros is on line:

Quote:
Dim C1 As Integer = DirectCast(row.FindControl("Label1"), TextBox).Text

This error will happen if i didn't put any values in the text box.. The error will be:

[FormatException: Input string was not in a correct format.]
   Microsoft.VisualBasic.CompilerServices.Conversions.ParseDouble(String Value, NumberFormatInfo NumberFormat) +205
   Microsoft.VisualBasic.CompilerServices.Conversions.ToInteger(String Value) +101

[InvalidCastException: Conversion from string "" to type 'Integer' is not valid.]
   Microsoft.VisualBasic.CompilerServices.Conversions.ToInteger(String Value) +259

My button to update my gridview..

Protected Sub Button1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button1.Click

        

        Dim rowcollect As GridViewRowCollection = GridView1.Rows
        Dim index As Integer = GridView1.SelectedIndex
        Dim cd As String = Session("CourseID")
        Dim id As String = Session("userID")
        Dim totQuiz, totC1, totC2, totC3, totC4, totC5 As Integer
        Dim totC6, totC7, totC8, totC9, totC10 As Integer


        For Each row As GridViewRow In rowcollect

            Dim C1 As Integer = DirectCast(row.FindControl("Label1"), TextBox).Text
            Dim C2 As Integer = DirectCast(row.FindControl("Label2"), TextBox).Text
            Dim C3 As Integer = DirectCast(row.FindControl("Label3"), TextBox).Text
            Dim C4 As Integer = DirectCast(row.FindControl("Label4"), TextBox).Text
            Dim C5 As Integer = DirectCast(row.FindControl("Label5"), TextBox).Text
            Dim C6 As Integer = DirectCast(row.FindControl("Label6"), TextBox).Text
            Dim C7 As Integer = DirectCast(row.FindControl("Label7"), TextBox).Text
            Dim C8 As Integer = DirectCast(row.FindControl("Label8"), TextBox).Text
            Dim C9 As Integer = DirectCast(row.FindControl("Label9"), TextBox).Text
            Dim C10 As Integer = DirectCast(row.FindControl("Label10"), TextBox).Text
            Dim sID As String = DirectCast(row.FindControl("Label11"), Label).Text


            'CID = GridView1.Rows(index).Cells(1).Text


            If row.RowType = DataControlRowType.DataRow Then

                If index = -1 Then
                    index = 0
                End If



                For i As Integer = 1 To row.Cells.Count - 1

                    Dim conn As New SqlConnection(ConfigurationManager.AppSettings("strConn"))
                    Dim MySQL As String = "UPDATE quiz SET CO1=@c1,CO2=@c2,CO3=@c3,CO4=@c4,CO5=@c5,CO6=@c6,CO7=@c7,CO8=@c8,CO9=@c9,CO10=@c10 WHERE CourseID=@cID AND stID=@id"
                    Dim cmd As SqlCommand = New SqlCommand(MySQL, conn)

                    cmd.Parameters.AddWithValue("@cID", cd.Trim)
                    cmd.Parameters.AddWithValue("@id", sID)


                    cmd.Parameters.Add(New SqlParameter("@c1", SqlDbType.Int, 4))
                    cmd.Parameters("@c1").Value = Convert.DBNull(C1)
                    totC1 += C1

                   
                    cmd.Parameters.Add(New SqlParameter("@c2", SqlDbType.Int, 4))
                    cmd.Parameters("@c2").Value = C2
                    totC2 += C2


                    cmd.Parameters.Add(New SqlParameter("@c3", SqlDbType.Int, 4))
                    cmd.Parameters("@c3").Value = C3
                    totC3 += C3

                    cmd.Parameters.Add(New SqlParameter("@c4", SqlDbType.Int, 4))
                    cmd.Parameters("@c4").Value = C4
                    totC4 += C4

                    cmd.Parameters.Add(New SqlParameter("@c5", SqlDbType.Int, 4))
                    cmd.Parameters("@c5").Value = C5
                    totC5 += C5

                    cmd.Parameters.Add(New SqlParameter("@c6", SqlDbType.Int, 4))
                    cmd.Parameters("@c6").Value = C6
                    totC6 += C6

                    cmd.Parameters.Add(New SqlParameter("@c7", SqlDbType.Int, 4))
                    cmd.Parameters("@c7").Value = C7
                    totC7 += C7

                    cmd.Parameters.Add(New SqlParameter("@c8", SqlDbType.Int, 4))
                    cmd.Parameters("@c8").Value = C8
                    totC8 += C8

                    cmd.Parameters.Add(New SqlParameter("@c9", SqlDbType.Int, 4))
                    cmd.Parameters("@c9").Value = C9
                    totC9 += C9

                    cmd.Parameters.Add(New SqlParameter("@c10", SqlDbType.Int, 4))
                    cmd.Parameters("@c10").Value = C10
                    totC10 += C10

                    totQuiz = C1 + C2 + C3 + C4 + C5 + C6 + C7 + C8 + C9 + C10

                    cmd.Parameters.Add(New SqlParameter("@total", SqlDbType.Int, 4))
                    cmd.Parameters("@total").Value = totQuiz



                    cmd.Connection.Open()
                    cmd.ExecuteNonQuery()
                    cmd.Connection.Close()

                Next
            End If
        Next

        totCO(totC1, totC2, totC3, totC4, totC5, totC6, totC7, totC8, totC9, totC10)


    End Sub

I try to put value '0' if the text box = Null, but it didn't work.
Its been few days I've been trying to find answers. Hope someone can suggest any idea for me to solve this.

modified 31-Oct-12 7:11am.

Eddy Vluggen15-Oct-12 0:48

Re: How to update Gridview with value textbox = Null

15-Oct-12 0:48

zaimah wrote:
I try to put value '0' if the text box = Null, but it didn't work.

Its been few days I've been trying to find answers. Hope someone can suggest any idea for me to solve this.

From

Dim C1 As Integer = DirectCast(row.FindControl("Label1"), TextBox).Text

Dim C1S As String = DirectCast(row.FindControl("Label1"), TextBox).Text
Dim C1 As Integer = Convert.ToInt32(C1S)

That should do it Smile | :)

Bastard Programmer from Hell Suspicious | :suss:

if you can't read my code, try converting it here[^]

zaimah15-Oct-12 5:46

Re: How to update Gridview with value textbox = Null

15-Oct-12 5:46

It didn't work with the same error. before this, the error is at:

Dim C1 As Integer = DirectCast(row.FindControl("Label1"), TextBox).Text

after i edit using your suggestion, the error is at:

Dim C1S As String = DirectCast(row.FindControl("Label1"), TextBox).Text

its as if it didn't even reach the convert part, the error occurred.. I have try similar method, trying to convert the value so that it can update the value Null to my table, but the error is still at the find control.. Is there something wrong with my coding at find control part? But the update is successful, except when the value is NULL..

This really gives me a headache.. Thanks for replying my question Smile | :)

Is there any solution?

Eddy Vluggen15-Oct-12 6:13

Re: How to update Gridview with value textbox = Null

15-Oct-12 6:13

zaimah wrote:
its as if it didn't even reach the convert part, the error occurred..

Put a breakpoint there and find out if it does, or does not execute.

zaimah wrote:
Is there something wrong with my coding at find control part?

That wouldn't change due to a value being empty, would it?

Didn't notice before, but you're looking for Label1 and casting it to a TextBox. Shouldn't that be a Label you're casting to?

Bastard Programmer from Hell Suspicious | :suss:

if you can't read my code, try converting it here[^]

zaimah15-Oct-12 13:48

Re: How to update Gridview with value textbox = Null

15-Oct-12 13:48

the name for textbox is Label1.. Sorry for the confusion Smile | :)

Originally, the gridview only have edit button for each row of data in gridview. So i change my gridview in html. I change all the label to textbox and bound the text box. So i would only have one button to update everything that i key-in in the gridview. After i change the label to textbox, lazy of me, im not changing the name of the previous label Poke tongue | ;-P

Would that effect the coding? But i can update the data. The problem is only when one of the textbox is empty. If the textbox that i cast for C10 is empty, then the error would be on C10, not C1.

Eddy Vluggen16-Oct-12 0:14

Re: How to update Gridview with value textbox = Null

16-Oct-12 0:14

C1 seems to be always containing NULL; from the code you pasted;

cmd.Parameters("@c1").Value = Convert.DBNull(C1)

Shouldn't that be an integer?

Bastard Programmer from Hell Suspicious | :suss:

if you can't read my code, try converting it here[^]

zaimah16-Oct-12 2:35

Re: How to update Gridview with value textbox = Null

16-Oct-12 2:35

Not always. If C1-C5 have value, and C6 is empty, then the error would be on C6. The weird thing is, the error only occur at textbox that are empty. It runs OK when there's no empty textbox.

Eddy Vluggen16-Oct-12 2:42

Re: How to update Gridview with value textbox = Null

16-Oct-12 2:42

That's not weird; you'll have to verify the users' input. If the database does not allow empty values (which it obviously doesn't), then you need to eliminate those before executing the query. It's either checking each value, or modify the database.

..you could copy the example-line, and add something similar to each parameter Smile | :)

Bastard Programmer from Hell Suspicious | :suss:

if you can't read my code, try converting it here[^]

zaimah16-Oct-12 2:59

Re: How to update Gridview with value textbox = Null

16-Oct-12 2:59

Do u mean the example that u gave me:

Dim C1S As Integer = DirectCast(row.FindControl("Label1"), TextBox).Text
            Dim C1 As Integer = Convert.ToInt32(C1S)

I have try using this method. It didn't work. How to check the value 1st and if its Null, put '0' in it?

the one that i put convert.dbnull is one of my testing. sorry for the confusion.

Sorry, my english s not that good Frown | :(

Eddy Vluggen16-Oct-12 3:17

Re: How to update Gridview with value textbox = Null

16-Oct-12 3:17

zaimah wrote:

Do u mean the example that u gave me:

Dim C1S As Integer = DirectCast(row.FindControl("Label1"), TextBox).Text
            Dim C1 As Integer = Convert.ToInt32(C1S)

That's not the example I gave you - the one you shown here tries to assign a string to an integer. This was the example;

Dim C1S As String = DirectCast(row.FindControl("Label1"), TextBox).Text
Dim C1 As Integer = Convert.ToInt32(C1S)

zaimah wrote:
Sorry, my english s not that good

It's good enough; we're making progress Smile | :)

zaimah wrote:
I have try using this method. It didn't work. How to check the value 1st and if its Null, put '0' in it?

The problem with the line is that it does multiple things at once; it contains multiple instructions. It get's easier if you divide it into smaller pieces, as smaller problems are easier to conquer.

So, first one needs to find the control. You already know how to do that;

Dim TextBoxC1 As TextBox = DirectCast(row.FindControl("TextBox1"), TextBox)

Then, put a breakpoint on that line, and make sure it can actually find the control. If it doesn't, it might generate an exception, claiming it's null.

Once you got the correct control, you get it's value. Keep in mind that textboxes (and labels) contain strings, and that an empty string might be equal to null again. For an integer, we'd do something like the example; Convert.ToInt32 will change a "null" to 0. If you're saving a string, you'd use Convert.ToString. So, the code would continue like this;

Dim TextBoxC1 As TextBox = DirectCast(row.FindControl("TextBox1"), TextBox)
Dim ValueC1 As String = Convert.ToString(TextBoxC1.Text) ' assuming you save a text, not a number

Once you got that, you can check whether "ValueC1" is "null" or an actual value (and replace it if required).

Bastard Programmer from Hell Suspicious | :suss:

if you can't read my code, try converting it here[^]

zaimah16-Oct-12 3:50

Re: How to update Gridview with value textbox = Null

16-Oct-12 3:50

i did like this

Dim C1S As TextBox = DirectCast(row.FindControl("TextBox1"), TextBox)
Dim C1 As Integer = Convert.ToInt32(C1S)

And the error is this:

[InvalidCastException: Unable to cast object of type 'System.Web.UI.WebControls.TextBox' to type 'System.IConvertible'.]
   System.Convert.ToInt32(Object value) +18

How can this be? my textbox suppose to have number as input not string. So i used convert.int32. Is this the correct way?

Eddy Vluggen16-Oct-12 4:21

Re: How to update Gridview with value textbox = Null

16-Oct-12 4:21

You're right, it's better if we look at them one at a time. A word of warning btw; I'm not a webdeveloper, just leaning on some general VB-knowledge.

Exception means that it can't find the control. That has to be fixed first, before we can convert values.

Dim C1S As TextBox = DirectCast(row.FindControl("TextBox1"), TextBox) 
Dim C1 As Integer = Convert.ToInt32(C1S)

As you can see, I'm looking for "TextBox1", which would have been "Label1" in your code. You already stated that you renamed it, so if you change it to the code below, it should find it;

Dim C1S As TextBox = DirectCast(row.FindControl("Label1"), TextBox) 
Dim C1 As Integer = Convert.ToInt32(C1S)

Like you said, it's a textbox, just named "Label1". The line after that should not throw an error.

Bastard Programmer from Hell Suspicious | :suss:

if you can't read my code, try converting it here[^]

zaimah17-Oct-12 4:13

Re: How to update Gridview with value textbox = Null

17-Oct-12 4:13

I did like your told me.. But the error is still the same.. I try to using this

Dim C1S As String = DirectCast(row.FindControl("Label1"), TextBox).Text
Dim C1 As Integer = Integer.TryParse(C1S, C1)

It works... it can update even with null value textbox. But another probem happens.. All of my value turn as negative in my table.. If i enter 1, it will be -1 in my table..

Eddy Vluggen17-Oct-12 4:51

Re: How to update Gridview with value textbox = Null

17-Oct-12 4:51

TryParse is indeed preferred over Convert.ToInt32. Didn't you find it weird that you had to add C1 as a parameter? It's not returning an integer (a number) but a boolean (y/no). Now, if we cast the boolean to an integer, it'll be -1. Could you try the value "42"? If it returns -42, a sign will be wrong, but I'm expecting it to return -1 also.

This should work;

Dim C1 As Integer = 0
Integer.TryParse(C1S, C1)

..with the boolean indicating whether the conversion to an integer was successful or not (since the string can contain "Hello world", and might not be able to return a number). That could also be used like below;

Dim C1 As Integer 
If Integer.TryParse(C1S, C1) Then
  'use C1
Else
  'couldn't be converted to a number, insert default
End If

Out of curiosity; when did you start with programming?

Bastard Programmer from Hell Suspicious | :suss:

if you can't read my code, try converting it here[^]

zaimah17-Oct-12 5:25