Date comparison StartDate should be greater than EndDate using C# and VB.Net in ASP.Net

Hi nauna,

Refer the below sample.

HTML

<div>
    Start Date:
    <asp:TextBox ID="txtStartDate" runat="server" Text="01/Jan/2016"></asp:TextBox>&nbsp;
    End Date:
    <asp:TextBox ID="txtEndDate" runat="server" Text="31/Dec/2015"></asp:TextBox><br />
    <asp:Button Text="Compare" runat="server" OnClick="Compare" />
</div>

C#

protected void Compare(object sender, EventArgs e)
{
    DateTime startDate = Convert.ToDateTime(txtStartDate.Text.Trim());
    DateTime endDate = Convert.ToDateTime(txtEndDate.Text.Trim());
    if (startDate > endDate)
    {
        // Doyour stuff.
    }
    else
    {
        ClientScript.RegisterClientScriptBlock(this.GetType(), "", "alert('Start date should be greate than End date')", true);
    }
}

VB.Net

Protected Sub Compare(sender As Object, e As EventArgs)
    Dim startDate As DateTime = Convert.ToDateTime(txtStartDate.Text.Trim())
    Dim endDate As DateTime = Convert.ToDateTime(txtEndDate.Text.Trim())
    ' Doyour stuff.
    If startDate > endDate Then
    Else
        ClientScript.RegisterClientScriptBlock(Me.[GetType](), "", "alert('Start date should be greate than End date')", True)
    End If
End Sub