Calculate Hours between two Dates in ASP.Net

Hi abc,

Please refer below sample.

HTML

<div>
    From Date:
    <asp:TextBox ID="txtfromdate" runat="server" Text="21-08-2018 10:10 AM" />
    <br />
    To Date:
    <asp:TextBox ID="txttodate" runat="server" Text="22-08-2018 05:40 PM" />
    <asp:Button ID="btnCalculate" OnClick="CalculateHours" Text="Calculate" runat="server" />
    <asp:Label ID="lblMessage" runat="server" />
</div>

Namespaces

C#

using System.Globalization;

VB.Net

Imports System.Globalization

Code

C#

protected void CalculateHours(object sender, EventArgs e)
{
    DateTime froDate = DateTime.ParseExact(txtfromdate.Text, "dd-MM-yyyy hh:mm tt", CultureInfo.InvariantCulture);
    DateTime toDate = DateTime.ParseExact(txttodate.Text, "dd-MM-yyyy hh:mm tt", CultureInfo.InvariantCulture);
    int fromHour = froDate.Hour;
    int fromMinute = froDate.Minute;
    int toMinute = toDate.Minute;
    int ToHour = toDate.Hour;
    int calculateMinute = toMinute - fromMinute;
    int calculateHour = ToHour - fromHour;
    string timeDiff = calculateHour.ToString("00") + ":" + calculateMinute.ToString("00");
    lblMessage.Text = "Calculated Time is :<b>" + timeDiff + "</b>";

}

VB.Net

Protected Sub CalculateHours(ByVal sender As Object, ByVal e As EventArgs)
    Dim froDate As DateTime = DateTime.ParseExact(txtfromdate.Text, "dd-MM-yyyy hh:mm tt", CultureInfo.InvariantCulture)
    Dim toDate As DateTime = DateTime.ParseExact(txttodate.Text, "dd-MM-yyyy hh:mm tt", CultureInfo.InvariantCulture)
    Dim fromHour As Integer = froDate.Hour
    Dim fromMinute As Integer = froDate.Minute
    Dim toMinute As Integer = toDate.Minute
    Dim ToHour As Integer = toDate.Hour
    Dim calculateMinute As Integer = toMinute - fromMinute
    Dim calculateHour As Integer = ToHour - fromHour
    Dim timeDiff As String = calculateHour.ToString("00") & ":" & calculateMinute.ToString("00")
    lblMessage.Text = "Calculated Time is :<b>" & timeDiff & "</b>"
End Sub

Screesnshot