var whitespace = " \t\n\r";

// Check whether string s is empty.
function isEmpty(s) {
	return ((s == null) || (s.length == 0))
}

// Returns true if string s is empty or 
// whitespace characters only.
function isEmptyField (s) {
	var i;
    // Is s empty?
    if (isEmpty(s)) return true;
    // Search through string's characters one by one
    // until we find a non-whitespace character.
    // When we do, return false; if we don't, return true.
    for (i = 0; i < s.length; i++) {
        // Check that current character isn't whitespace.
        var c = s.charAt(i);
        if (whitespace.indexOf(c) == -1) return false;
    }
    // All characters are whitespace.
   return true;
}

function isNotSelected (s) {
	if (s.selectedIndex == 0) 
	{
		return true;
	}
	return false;
}

function isEmail (s) {
    // is s whitespace?
    if (isEmptyField(s)) return false;
    // there must be >= 1 character before @, so we
    // start looking at character position 1 
    // (i.e. second character)
    var i = 1;
    var sLength = s.length;
    // look for @
    while ((i < sLength) && (s.charAt(i) != "@"))
    { i++
    }
    if ((i >= sLength) || (s.charAt(i) != "@")) return false;
    else i += 2;
    // look for .
    while ((i < sLength) && (s.charAt(i) != "."))
    { i++
    }
    // there must be at least one character after the .
    if ((i >= sLength - 1) || (s.charAt(i) != ".")) return false;
    else return true;
}

// Returns true if character c is a digit 
// (0 .. 9).

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

function val_null(str) {
	if (str.length == 0 )
		return  'null' ;
	else
		return  str ;
}