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

function isEmail (s)
{   if (isEmpty(s)) 
       if (isEmail.arguments.length == 1) return false;
       else return (isEmail.arguments[1] == true);
   
    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 isWhitespace (s)

{   var i;

    if (isEmpty(s)) return true;

    for (i = 0; i < s.length; i++)
    {   
        var c = s.charAt(i);

        if (whitespace.indexOf(c) == -1) return false;
    }

    return true;
}

function isEmpty(s)
{   return ((s == null) || (s.length == 0))
}


function isInteger (s)

{   var i;

    if (isEmpty(s)) 
       if (isInteger.arguments.length == 1) return defaultEmptyOK;
       else return (isInteger.arguments[1] == true);

    // Search through string's characters one by one
    // until we find a non-numeric character.
    // When we do, return false; if we don't, return true.

    for (i = 0; i < s.length; i++)
    {   
        // Check that current character is number.
        var c = s.charAt(i);

        if (!isDigit(c)) return false;
    }

    // All characters are numbers.
    return true;
}

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