function validatePostnr(){
	if(isNaN(document.sogeForm.postnr.value) || document.sogeForm.postnr.length<4){
		alert('Du har indtastet et ugyldigt postnummer');
		document.sogeForm.postnr.select();
		return false;
	} else {
		return true;
	}
}
	
function calcAntalDogn(){

	var fraDate = new Date();
	var tilDate = new Date();
	var today = new Date();
	var firstAugust = new Date();

	var strFra = document.getElementById('fraDato').value;
	var strTil = document.getElementById('tilDato').value;
	
	var splitFraDate = strFra.split("-");
	var splitTilDate = strTil.split("-");
	
	var fraDag = splitFraDate[0];
	var fraMaaned = splitFraDate[1];
	var fraAar = splitFraDate[2];

	var tilDag = splitTilDate[0];
	var tilMaaned = splitTilDate[1];
	var tilAar = splitTilDate[2];

	var videre_btn = document.getElementById('videre_btn');

	if(fraDag.length > 0 && fraMaaned.length > 0 && fraAar.length > 0 && tilDag.length > 0 && tilMaaned.length > 0 && tilAar.length > 0){
					
		fraDate.setFullYear(fraAar,fraMaaned-1,fraDag);
		tilDate.setFullYear(tilAar,tilMaaned-1,tilDag);
	
		if (fraDate.getTime() > tilDate.getTime()){
			alert('Hjemkomstdatoen skal være senere end afrejsedatoen '+ strFra);
			videre_btn.disabled = true;
			return false;
		}else if (fraDate.getTime() < today.getTime() || tilDate.getTime() < today.getTime()){
			alert('Du kan ikke booke tilbage i tiden');
			videre_btn.disabled = true;
			return false;
		}else if (fraDate.getTime() <= tilDate.getTime()){
			diff = tilDate.getTime() - fraDate.getTime();
			diff = Math.ceil(diff / (1000 * 60 * 60 * 24));
			diff++
		}else{
			diff = 0
		}
		
		document.getElementById("antalDogn").innerHTML = diff;
		document.pkortForm.antalDogn.value = diff;
		
/*		if(diff < 7){
			antal40dage = diff;
			antal25dage = 0;
			dblRabat = 0;
		}else{
			antal40dage = 7;
			if(diff-8 > 0){
				antal25dage = diff -  8;
			}else{
				antal25dage = 0;
			}
			dblRabat = 55;
		}
		
		intAntalDogn = document.getElementById('antalDogn').value;
*/		
		videre_btn.disabled = false;
		
	}
	else
	{
		videre_btn.disabled = true;
	}
}