text box validation in asp.net c#

You can use the custom validation tags to do this. But you would have to do some javascript as well. This works well for checking if the text boxes have values as well, by using this:

<asp:RequiredFieldValidator ID="RequiredFieldValidator2" runat="server" ErrorMessage="Please enter date one"
               ValidationGroup="validationGroup" Display="None" ControlToValidate="txtDateOne" /> 

And then for the custom tag have something like this:

<asp:customvalidator id=""CustomValidator1"" runat=""server"" display=""None"" errormessage=""Please" make="" sure="" there="" is="" a="" one="" year="" mode="hold" xmlns:asp="#unknown" />                ValidationGroup="validationGroup" ClientValidationFunction="validateCorrespondence"></asp:CustomValidator>

In the client validation field you can pass the javascript function name that checks the two dates

try that way

function getTimeDiff(){
    var txtBoxStartDate = document.getElementById('<%=txtBoxStartDate.ClientID%>');
    var txtBoxEndDate = document.getElementById('<%=txtBoxEndDate.ClientID%>');

    var dtStart = new Date(txtBoxStartDate.value);
    var dtEnd = new Date(txtBoxEndDate.value);

    var diff = Math.floor((dtEnd.getTime() - dtStart.getTime())/(1000*60*60*24));
   alert(''The diff between dates is " + diff )

}

Try:

if (todate >= fromdate.AddYears(1))
   {
   ...
   }

MSDN[^]


"Actually if i enter a date like 31-12-1984 then how it check 01-01-1985 the difference between two date is only one day."


Yes. And AddYears adds a whole year to the from date, making it 31-12-1985...

DateTime from = new DateTime(1984, 12, 31);
DateTime to = new DateTime(1985, 1, 1);
if (to >= from.AddYears(1))
{
    Console.WriteLine("Greater");
}
else
{
    Console.WriteLine("Less");
}

Prints "Less"

Hi,

check it in javascript if the second text box value greater than the first textbox value...


check this this for calculating age...convert it to your use.
function test()
{
// alert("hai");
debugger;


var bday =document.getElementById('<%=date.ClientID%>').value
var bmo =document.getElementById('<%=month.ClientID%>').value
var byr =document.getElementById('<%=year.ClientID%>').value


var byr;
var age;
var now = new Date();
var tday=now.getDate();
var tmo=(now.getMonth());
var tyr=(now.getFullYear());
{
if((tmo > bmo)||(tmo==bmo & tday>=bday))
{age=byr}
else
{age=byr+1}
alert("As of today, "+now+' \n'+", you are:"+(tyr-age)+ " years old");


}
}

regards,
shefeek