<form ... name="uhrzeit">

	<input type="text" name="stundeA" value="" ... />
	<input type="text" name="minuteA" value="" ... />
	<input type="text" name="sekundeA" value="" ... />
	
	<input onkeyup="this.form.stundeERGEBNIS.value = this.form.stundeA.value - this.value" type="text" name="stundeB" ... />
	<input onkeyup="this.form.minuteERGEBNIS.value = this.form.minuteA.value - this.value" type="text" name="minuteB" ... />
	<input onkeyup="this.form.sekundeERGEBNIS.value = this.form.sekundeA.value - this.value" type="text" name="sekundeB" ... />
	
	<input type="text" name="stundeERGEBNIS" value="" ... />
	<input type="text" name="minuteERGEBNIS" value="" ... />
	<input type="text" name="sekundeERGEBNIS" value="" ... />

</form>

<script language=JavaScript> 

var uhrzeitA = new Date(); 
var uhrzeitB = new Date(); 
   
function umrechnen() 
{ 
	window.document.form.stundeA.value = uhrzeitA.setHours()
	window.document.form.minuteA.value = uhrzeitA.setMinutes()
	window.document.form.sekundeA.value = uhrzeitA.setSeconds()
	
	window.document.form.stundeB.value = uhrzeitB.setHours()
	window.document.form.minuteB.value = uhrzeitB.setMinutes()
	window.document.form.sekundeB.value = uhrzeitB.setSeconds()
} 
   
</script>

#include <windows.h>
#include <iostream>

using namespace std;

int main()
{
int sekunden_gesamt = 23456;
int s = 1, m = 60, h = 3600;
int rest, stunden, minuten, sekunden;

char szZeit[12];

stunden = sekunden_gesamt / h;
rest = sekunden_gesamt - (stunden * h);

minuten = rest / m;
rest = rest - (minuten * m);

sekunden = rest / s;

wsprintf(szZeit, "[%02d:%02d:%02d]", stunden, minuten, sekunden);

        cout<< szZeit;

        cin.get();
return 0;
}

<script type="text/javascript">

		function Zero(TElement)
		{

			return (TElement<10) ? '0'+String(TElement) : String(TElement);

		}

		function CalcDiff()
		{

			with (document.FCalcT)
			{

				SecT1=(parseInt(T1H.value)*60*60)+(parseInt(T1M.value)*60)+parseInt(T1S.value);
				SecT2=(parseInt(T2H.value)*60*60)+(parseInt(T2M.value)*60)+parseInt(T2S.value);

				if (SecT2<SecT1)
				{

					alert('Zeitangeben nicht korrekt ...');

				}
				else
				{

					SecRes=SecT2-SecT1;

					TRS.value=Zero(parseInt(SecRes % 60));
					TRM.value=Zero(parseInt((SecRes/60) % 60));
					TRH.value=Zero(parseInt((SecRes/60/60)));

				}

			}

		}

	</script>

	<form name="FCalcT">

		Zeit 1

		<input name="T1H" size="2" value="" maxlength="2">:<input name="T1M" size="2" value="" maxlength="2">:<input name="T1S" size="2"value=""  maxlength="2">

		


		Zeit 2

		<input name="T2H" size="2" value="" maxlength="2">:<input name="T2M" size="2" value="" maxlength="2">:<input name="T2S" size="2" value="" maxlength="2">

		



		<input type="button" value="Differenz" onClick="CalcDiff()">

		



		Differenz

		<input name="TRH" size="2" value="00">:<input name="TRM" size="2" value="00">:<input name="TRS" size="2" value="00">

	</form>

<script type="text/javascript">

var uhrzeitA = new Date();
var uhrzeitB = new Date(); 

if(!Date.diff) {
  Date.prototype.diff = function() {
    alert(Date.parse(String(uhrzeitA))-Date.parse(String(uhrzeitB)));
  }
}

var objDate = new Date();
objDate.diff();
</script>