function check_login(dove) {
 	var username = document[dove].username;
 	var password = document[dove].password;
	if(username.value.length < 2) {
	 	alert("Specificare almeno due caratteri per il campo username!");
	 	username.focus();
	 	return false;
	}
	if(password.value.length < 2) {
	 	alert("Specificare almeno due caratteri per il campo password!");
	 	password.focus();
	 	return false;
	}
}


function emailCheck(emailStr) {
    var emailPat = /^(.+)@(.+)$/;
    var specialChars = "\\(\\)<>@,;:\\\\\\\"\\.\\[\\]";
    var validChars = "[^\\s" + specialChars + "]";
    var quotedUser = "(\"[^\"]*\")";
    var ipDomainPat = /^\[(\d{1,3})\.(\d{1,3})\.(\d{1,3})\.(\d{1,3})\]$/;
    var atom = validChars + "+";
    var word = "(" + atom + "|" + quotedUser + ")";
    var userPat = new RegExp("^" + word + "(\\." + word + ")*$");
    var domainPat = new RegExp("^" + atom + "(\\." + atom + ")*$");
    var matchArray = emailStr.match(emailPat);
    if (matchArray == null) {
        alert("Verify your e-mail address");
        return false;
    }
    var user = matchArray[1];
    var domain = matchArray[2];
    if (user.match(userPat) == null) {
        alert("Verify your e-mail address!");
        return false;
    }
    var IPArray = domain.match(ipDomainPat);
    if (IPArray != null) {
        for (var i = 1; i <= 4; i++) {
            if (IPArray[i] > 255) {
                alert("The ip address of destination is not valid!");
                return false;
            }
        }
    }
    var domainArray = domain.match(domainPat);
    if (domainArray == null) {
        alert("Verify your e-mail address!");
        return false;
    }
    var atomPat = new RegExp(atom, "g");
    var domArr = domain.match(atomPat);
    var len = domArr.length;
    if (domArr[domArr.length - 1].length < 2 ||
        domArr[domArr.length - 1].length > 6) {
        alert("The domain of your e-mail is not valid!");
        return false;
    }
    if (len < 2) {
        var errStr = "Verify your e-mail address!";
        alert(errStr);
        return false;
    }
    
}