function getQuestionValueByName(name) {
	var obj = document.getElementsByName(name);
	for(var i=0; i<obj.length; i++)
		if(obj[i].checked)
			return(obj[i].value);
	return('-1');
}

function getNumQuestion(name) {
	var strName = new String(name);
	return(strName.substring(1,strName.indexOf('_',1)));
}

function checkRequired() {
	var questions = document.getElementsByName('fields')[0].value;
	var strQuestions = new String(questions);
	var arrQuestions = strQuestions.split(';');
	var value;
	for(var i=0; i<arrQuestions.length; i++) {
		value = getQuestionValueByName(arrQuestions[i]);
		if(value=='-1') {
			var question = getNumQuestion(arrQuestions[i]);
			alert('Veuillez répondre à la question '+question);
			return false;
		}
	}
	return true;
}