Calculate GridView Time column Sum in HH:mm format on Button Click using C# and VB.Net in ASP.Net

Hi democloud,

Check the below code.

HTML

<asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="false">
    <Columns>
        <asp:BoundField DataField="Dates" HeaderText="Date" />
        <asp:BoundField DataField="Day" HeaderText="Day" />
        <asp:TemplateField HeaderText="Normal">
            <ItemTemplate>
                <asp:TextBox runat="server" ID="txtNormalHours" Text='<%#Eval("NormalHours") %>' />
            </ItemTemplate>
        </asp:TemplateField>
        <asp:TemplateField HeaderText="Weekend">
            <ItemTemplate>
                <asp:TextBox runat="server" ID="txtWeekendHours" Text='<%#Eval("WeekendHours") %>' />
            </ItemTemplate>
        </asp:TemplateField>
    </Columns>
</asp:GridView>
<br />
<asp:Button Text="Insert" runat="server" OnClick="Insert" />
<br />
<br />
<asp:TextBox runat="server" ID="txtTotal" />

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[] { 
                    new System.Data.DataColumn("Dates", typeof(string)),
                    new System.Data.DataColumn("Day", typeof(string)),
                    new System.Data.DataColumn("NormalHours",typeof(string)),
                    new System.Data.DataColumn("WeekendHours",typeof(string)),
                    new System.Data.DataColumn("Time",typeof(string)) });
        dt.Rows.Add("11/04/2019", "Monday", "03:00:00", "4.5", "12:00pm 03:00pm");
        dt.Rows.Add("11/04/2019", "Monday", "00:30:00", "5.5", "09:30am 10:00am");
        dt.Rows.Add("11/11/2019", "Monday", "03:00:00", "4", "12:00pm 03:00pm");
        dt.Rows.Add("11/11/2019", "Monday", "00:30:00", "2", "09:30am 10:00am");
        dt.Rows.Add("11/11/2019", "Monday", "06:00:00", "0", "01:00am 06:00am");
        GridView1.DataSource = dt;
        GridView1.DataBind();
    }
}

protected void Insert(object sender, EventArgs e)
{
    TimeSpan new_normal = new TimeSpan();
    foreach (GridViewRow row in GridView1.Rows)
    {
        TextBox normal = (TextBox)(row.FindControl("txtNormalHours"));
        TextBox weekend = (TextBox)(row.FindControl("txtWeekendHours"));
        TimeSpan normal_hours = TimeSpan.Parse(normal.Text) + TimeSpan.FromHours(Convert.ToDouble(weekend.Text));
        new_normal = new_normal + normal_hours;
    }
    txtTotal.Text = ((int)new_normal.TotalHours).ToString().PadLeft(2, '0') + ":" + new_normal.Minutes.ToString().PadLeft(2, '0');
}

VB.Net

Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs) Handles Me.Load
    If Not IsPostBack Then
        Dim dt As Data.DataTable = New Data.DataTable()
        dt.Columns.AddRange(New Data.DataColumn() {New Data.DataColumn("Dates", GetType(String)),
                                                New Data.DataColumn("Day", GetType(String)),
                                                New Data.DataColumn("NormalHours", GetType(String)),
                                                New Data.DataColumn("WeekendHours", GetType(String)),
                                                New Data.DataColumn("Time", GetType(String))})
        dt.Rows.Add("11/04/2019", "Monday", "03:00:00", "4.5", "12:00pm 03:00pm")
        dt.Rows.Add("11/04/2019", "Monday", "00:30:00", "5.5", "09:30am 10:00am")
        dt.Rows.Add("11/11/2019", "Monday", "03:00:00", "4", "12:00pm 03:00pm")
        dt.Rows.Add("11/11/2019", "Monday", "00:30:00", "2", "09:30am 10:00am")
        dt.Rows.Add("11/11/2019", "Monday", "06:00:00", "0", "01:00am 06:00am")
        GridView1.DataSource = dt
        GridView1.DataBind()
    End If
End Sub

Protected Sub Insert(ByVal sender As Object, ByVal e As EventArgs)
    Dim new_normal As TimeSpan = New TimeSpan()
    For Each row As GridViewRow In GridView1.Rows
        Dim normal As TextBox = CType((row.FindControl("txtNormalHours")), TextBox)
        Dim weekend As TextBox = CType((row.FindControl("txtWeekendHours")), TextBox)
        Dim normal_hours As TimeSpan = TimeSpan.Parse(normal.Text) + TimeSpan.FromHours(Convert.ToDouble(weekend.Text))
        new_normal = new_normal + normal_hours
    Next
    txtTotal.Text = (CInt(new_normal.TotalHours)).ToString().PadLeft(2, "0"c) & ":" + new_normal.Minutes.ToString().PadLeft(2, "0"c)
End Sub

Screenshot