function isDigit (c)
	{   
		return ((c >= "0") && (c <= "9"))
	}

function isInteger (s)
	{
		var i;

		for (i = 0; i < s.length; i++)
    		{
			var c = s.charAt(i);
			if (!isDigit(c))
				return false;
    		}

		return true;
}

function isWhitespace (s) {
	var i;
	var whitespace = " \t\n\r";
	
	for (i = 0; i < s.length; i++)
		{
			var c = s.charAt(i);
			if (whitespace.indexOf(c) == -1) return false;
		}
	return true;
}

function isEmail (s)
{
    if (isWhitespace(s)) return false;

    var i = 1;
    var sLength = s.length;
    while ((i < sLength) && (s.charAt(i) != "@"))
    	{
    		i++
    	}
    
    if ((i >= sLength) || (s.charAt(i) != "@")) return false;
    else i += 2;
    
    while ((i < sLength) && (s.charAt(i) != "."))
    	{ 
    		i++
    	}
    
    if ((i >= sLength - 1) || (s.charAt(i) != ".")) return false;
    else return true;
}


function checkfields(form)
	{
	
	if (form.name.value == "")
		{
		alert("Please enter your first name.");
		form.name.focus();
		return false;
		}
		
	if (form.email.value == "")
		{
		alert("Please enter your email address.");
		form.email.focus();
		return false;
		}
	
	if (!isEmail(form.email.value))
		{
		alert("You did not enter a valid e-mail address.");
		form.email.focus();
		return false;
		}
		
	}