function isEmail(email) //if the string is a valid mail address
{
    var reg_email = /^([a-zA-Z0-9_\.\-])+\@(([a-zA-Z0-9\-])+\.)+([a-zA-Z0-9]{2,4})+$/;
    return email.match(reg_email);
}

function isString(string) //if the string is only compose of letter
{
	var reg_string = /^[a-zA-Z]+$/;
	return string.match(reg_string);
}

function isInt(number) //if the string is only compose of digits
{
	var reg_number = /^[0-9]+$/;
	return number.match(reg_number);
}

function isFloat(number) //if the string is compose of digits and a "."
{
	var reg_float = /^([0-9]+).([0-9]{1,3})$/;
	if(number.match(reg_float) || isInt(number))
	{
        return true;
	}
	return false;
}

function isAlphanumerical(string) //if the string is only compose of digits
{
	var reg_alphanum = /^[a-zA-Z0-9]+$/;
	return string.match(reg_alphanum);
}

function isMinSize(str, size)
{
	retour=false;
	if(str.length>=size)
		retour=true;
	return retour;
}