Adjust TextBox value in GridView row based on TextBox using C# and VB.Net in ASP.Net

Hi akhter,

Check this example. Now please take its reference and correct your code.

HTML

<div>
    Cheque Amount<asp:TextBox ID="chqamount" runat="server" Text="500"></asp:TextBox>
    <br />
    Cheque No :<asp:TextBox ID="chequno" runat="server" Text="123"></asp:TextBox>
    <asp:Button ID="btn_Adj" runat="server" Text="Adjust_Amount" OnClick="AdjustAmount" />
    <br />
    <br />
    <asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="false">
        <Columns>
            <asp:TemplateField HeaderText=" ID">
                <ItemTemplate>
                    <asp:Label ID="I_ID" runat="server" Text='<%#Bind("I_ID")%>'></asp:Label>
                </ItemTemplate>
            </asp:TemplateField>
            <asp:TemplateField HeaderText=" Amount">
                <ItemTemplate>
                    <asp:Label ID="I_Amt" runat="server" Text='<%#Bind("I_Amt")%>'></asp:Label>
                </ItemTemplate>
            </asp:TemplateField>
            <asp:TemplateField HeaderText=" Cheque_NO">
                <ItemTemplate>
                    <asp:TextBox ID="C_NO" runat="server" ReadOnly="true" Text='0'></asp:TextBox>
                </ItemTemplate>
            </asp:TemplateField>
            <asp:TemplateField HeaderText=" Cheque_Amount">
                <ItemTemplate>
                    <asp:TextBox ID="C_Amt" runat="server" ReadOnly="true" Text='0'></asp:TextBox>
                </ItemTemplate>
            </asp:TemplateField>
            <asp:TemplateField HeaderText="Status">
                <ItemTemplate>
                    <asp:DropDownList ID="ddlStatus" runat="server">
                        <asp:ListItem Text="Pending" Value="1" Selected="True"></asp:ListItem>
                        <asp:ListItem Text="Received" Value="2" />
                    </asp:DropDownList>
                </ItemTemplate>
            </asp:TemplateField>
        </Columns>
    </asp:GridView>
</div>

Code

C#

protected void Page_Load(object sender, EventArgs e)
{
    if (!IsPostBack)
    {
        System.Data.DataTable dt = new System.Data.DataTable();
        dt.Columns.AddRange(new System.Data.DataColumn[2] { 
                        new System.Data.DataColumn("I_ID", typeof(int)),
                        new System.Data.DataColumn("I_Amt", typeof(int)) });
        dt.Rows.Add(21, 339);
        dt.Rows.Add(22, 622);
        dt.Rows.Add(23, 226);
        dt.Rows.Add(26, 339);
        dt.Rows.Add(27, 339);
        GridView1.DataSource = dt;
        GridView1.DataBind();
    }
}

protected void AdjustAmount(object sender, EventArgs e)
{
    int chequeAmount = Convert.ToInt32(chqamount.Text);
    foreach (GridViewRow row in GridView1.Rows)
    {
        int id = Convert.ToInt32((row.FindControl("I_ID") as Label).Text);
        int amount = Convert.ToInt32((row.FindControl("I_Amt") as Label).Text);
        TextBox txtCheque = row.FindControl("C_NO") as TextBox;
        TextBox txtAmount = row.FindControl("C_Amt") as TextBox;
        DropDownList ddl = row.FindControl("ddlStatus") as DropDownList;

        if (chequeAmount >= amount)
        {
            txtCheque.Text = chequno.Text;
            txtAmount.Text = amount.ToString();
            chequeAmount = chequeAmount - amount;
        }
        else if (chequeAmount < amount && chequeAmount > 0)
        {
            txtCheque.Text = chequno.Text;
            txtAmount.Text = chequeAmount.ToString();
            chequeAmount = 0;
        }
        else
        {
            txtCheque.Text = "0";
            txtAmount.Text = "0";
        }

        ddl.ClearSelection();
        if (amount == Convert.ToInt32(txtAmount.Text))
        {
            ddl.Items.FindByText("Received").Selected = true;
        }
        else
        {
            ddl.Items.FindByText("Pending").Selected = true;
        }
    }
}

VB.Net

Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs) Handles Me.Load
    If Not IsPostBack Then
        Dim dt As System.Data.DataTable = New System.Data.DataTable()
        dt.Columns.AddRange(New System.Data.DataColumn(1) {
                            New System.Data.DataColumn("I_ID", GetType(Integer)),
                            New System.Data.DataColumn("I_Amt", GetType(Integer))})
        dt.Rows.Add(21, 339)
        dt.Rows.Add(22, 622)
        dt.Rows.Add(23, 226)
        dt.Rows.Add(26, 339)
        dt.Rows.Add(27, 339)
        GridView1.DataSource = dt
        GridView1.DataBind()
    End If
End Sub

Protected Sub AdjustAmount(ByVal sender As Object, ByVal e As EventArgs)
    Dim chequeAmount As Integer = Convert.ToInt32(chqamount.Text)
    For Each row As GridViewRow In GridView1.Rows
        Dim id As Integer = Convert.ToInt32((TryCast(row.FindControl("I_ID"), Label)).Text)
        Dim amount As Integer = Convert.ToInt32((TryCast(row.FindControl("I_Amt"), Label)).Text)
        Dim txtCheque As TextBox = TryCast(row.FindControl("C_NO"), TextBox)
        Dim txtAmount As TextBox = TryCast(row.FindControl("C_Amt"), TextBox)
        Dim ddl As DropDownList = TryCast(row.FindControl("ddlStatus"), DropDownList)

        If chequeAmount >= amount Then
            txtCheque.Text = chequno.Text
            txtAmount.Text = amount.ToString()
            chequeAmount = chequeAmount - amount
        ElseIf chequeAmount < amount AndAlso chequeAmount > 0 Then
            txtCheque.Text = chequno.Text
            txtAmount.Text = chequeAmount.ToString()
            chequeAmount = 0
        Else
            txtCheque.Text = "0"
            txtAmount.Text = "0"
        End If

        ddl.ClearSelection()
        If amount = Convert.ToInt32(txtAmount.Text) Then
            ddl.Items.FindByText("Received").Selected = True
        Else
            ddl.Items.FindByText("Pending").Selected = True
        End If
    Next
End Sub

Screenshot