function ctrlCheck() {
	if(document.search_pref.check_ctrl.value == "Check all"){
		document.search_pref.check_ctrl.value = "Clear all";
		for (var i=0; i<document.search_pref.use.length; i++) {
			document.search_pref.use[i].checked = true;
		}	
	}else{
		document.search_pref.check_ctrl.value = "Check all";
		for (var i=0; i<document.search_pref.use.length; i++) {
			document.search_pref.use[i].checked = false;
		}
	}
}

function gotoSearch(){
	if($('q').value != ""){
		return true;
	}else{
		alert("The input field is empty.");
		return false;
	}
}

function getCheckedNum(){
	var count = 0;
	for (var i=0; i<document.search_pref.use.length; i++) {
		if(document.search_pref.use[i].checked) {
			count++;
		}
	}
	return count;
}

function savePreferences(){
	if(getCheckedNum()){
		var params = '';
		for (var i=0; i<document.search_pref.use.length; i++) {
			params += document.search_pref.use[i].value + '=' + document.search_pref.use[i].checked + '&';
		}
		params += 'slider=' + $('slider').value + '&';
		params += 'num=' + $('num').value;
				
		$('send').value = params;
		alert("Your Preferences has been saved.");
		return true;
	}else{
		alert("Check the box used for a search.");
		return false;
	}
}