Subtract ASP.Net GridView rows and show result using C# and VB.Net

Hi mansoorkpy,

Refer below example.

HTML

<asp:GridView runat="server" ID="gvTimes" AutoGenerateColumns="false">
    <Columns>
        <asp:BoundField DataField="Id" HeaderText="Id" />
        <asp:BoundField DataField="StartTime" HeaderText="Start" DataFormatString="{0:HH:mm}" />
        <asp:BoundField DataField="EndTime" HeaderText="End" DataFormatString="{0:HH:mm}" />
        <asp:TemplateField HeaderText="Difference">
            <ItemTemplate>
                <asp:Label ID="lblDiff" runat="server" Text="0" />
            </ItemTemplate>
        </asp:TemplateField>
    </Columns>
</asp:GridView>

Namespaces

C#

using System.Data;

VB.Net

Imports System.Data

Code

C#

protected void Page_Load(object sender, EventArgs e)
{
    if (!this.IsPostBack)
    {
        DataTable dt = new DataTable();
        dt.Columns.Add("Id", typeof(int));
        dt.Columns.Add("StartTime", typeof(DateTime));
        dt.Columns.Add("EndTime", typeof(DateTime));
        dt.Rows.Add(1, DateTime.Now, DateTime.Now);
        dt.Rows.Add(2, DateTime.Now.AddHours(1), DateTime.Now);
        dt.Rows.Add(3, DateTime.Now.AddHours(2), DateTime.Now);
        gvTimes.DataSource = dt;
        gvTimes.DataBind();

        for (int i = 0; i < dt.Rows.Count; i++)
        {
            if (i < dt.Rows.Count - 1)
            {
                DateTime endTime = Convert.ToDateTime(dt.Rows[i][2]);
                DateTime startTime = Convert.ToDateTime(dt.Rows[i + 1][1]);
                (gvTimes.Rows[i + 1].FindControl("lblDiff") as Label).Text = startTime.Subtract(endTime).Hours.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 DataTable = New DataTable()
        dt.Columns.Add("Id", GetType(Integer))
        dt.Columns.Add("StartTime", GetType(DateTime))
        dt.Columns.Add("EndTime", GetType(DateTime))
        dt.Rows.Add(1, DateTime.Now, DateTime.Now)
        dt.Rows.Add(2, DateTime.Now.AddHours(1), DateTime.Now)
        dt.Rows.Add(3, DateTime.Now.AddHours(2), DateTime.Now)
        gvTimes.DataSource = dt
        gvTimes.DataBind()
        For i As Integer = 0 To dt.Rows.Count - 1 Step 1
            If i < dt.Rows.Count - 1 Then
                Dim endTime As DateTime = Convert.ToDateTime(dt.Rows(i)(2))
                Dim startTime As DateTime = Convert.ToDateTime(dt.Rows(i + 1)(1))
                TryCast(gvTimes.Rows(i + 1).FindControl("lblDiff"), Label).Text = startTime.Subtract(endTime).Hours.ToString()
            End If
        Next
    End If
End Sub

Screenshot