Display two ASP.Net GridView columns total in Third on Button Click using C# and VB.Net

Hi nabilabolo,

Refer below code.

HTML

<asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="false">
    <Columns>
        <asp:BoundField DataField="Quantity" HeaderText="Quantity" />
        <asp:BoundField DataField="Cost" HeaderText="Cost" />
        <asp:TemplateField HeaderText="Total">
            <ItemTemplate>
                <asp:Label ID="lblTotal" runat="server" />
            </ItemTemplate>
        </asp:TemplateField>
    </Columns>
</asp:GridView>
<asp:Button Text="Calculate" runat="server" OnClick="OnCalculate" />

Code

C#

protected void Page_Load(object sender, EventArgs e)
{
    if (!this.IsPostBack)
    {
        System.Data.DataTable dt = new System.Data.DataTable();
        dt.Columns.AddRange(new System.Data.DataColumn[]
        {
            new System.Data.DataColumn("Quantity"),
            new System.Data.DataColumn("Cost")
        });
        dt.Rows.Add(30, 5);
        dt.Rows.Add(100, 21);
        GridView1.DataSource = dt;
        GridView1.DataBind();
    }
}

protected void OnCalculate(object sender, EventArgs e)
{
    foreach (GridViewRow row in GridView1.Rows)
    {
        decimal quantity = Convert.ToDecimal(row.Cells[0].Text);
        decimal cost = Convert.ToDecimal(row.Cells[1].Text);
        (row.FindControl("lblTotal") as Label).Text = Math.Round(((cost / quantity) * 100), 2).ToString();
    }
}

VB.Net

Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs) Handles Me.Load
    If Not Me.IsPostBack Then
        Dim dt As Data.DataTable = New Data.DataTable()
        dt.Columns.AddRange(New Data.DataColumn() {
                            New Data.DataColumn("Quantity"),
                            New Data.DataColumn("Cost")})
        dt.Rows.Add(30, 5)
        dt.Rows.Add(100, 21)
        GridView1.DataSource = dt
        GridView1.DataBind()
    End If
End Sub

Protected Sub OnCalculate(ByVal sender As Object, ByVal e As EventArgs)
    For Each row As GridViewRow In GridView1.Rows
        Dim quantity As Decimal = Convert.ToDecimal(row.Cells(0).Text)
        Dim cost As Decimal = Convert.ToDecimal(row.Cells(1).Text)
        TryCast(row.FindControl("lblTotal"), Label).Text = Math.Round(((cost / quantity) * 100), 2).ToString()
    Next
End Sub

Output

Quantity Cost Total

   30          5      16.66

  100         21    21.00