function setImage(id, filename){
	document.getElementById(id).src=filename;
}
function showImage(id, main_class){
	var elems = document.getElementsByTagName('div');
	for(var i=0;i<elems.length;i++){
		if(elems[i].className==main_class){
			elems[i].style.display = 'none';
		}
	}

	document.getElementById(id).style.display = 'block';
}





//validation function for registration form
function validateContact(email){
	if(!validate())
		return false
	if(!validateEmailAddress(email))
		return false
	return true;
}


//check that all fields with classname 'required' are filled in
function validate(){
var elems=document.getElementsByTagName('input'); 
for(var i=0;i<elems.length;i++){
	if((elems[i].className=='required')&&(elems[i].value=="")){
		alert("Please fill in all required fields");
		return false;
	}
}
return true;
}


/*** This validation function checks that an email address contains both '@' and '.' **/
function validateEmailAddress(email_address){
var email = document.getElementById(email_address).value;
	if((email.indexOf('@')==-1)||(email.indexOf('.')==-1)){
		alert("Invalid email address");
		return false;
	}
	else
		return true;
}