var digitsInZIPCode1 = 5;

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

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

function isLetter (c)
{   return ( ((c >= "a") && (c <= "z")) || ((c >= "A") && (c <= "Z")) )
}



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


function isWhitespace (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 isAlphanumeric (s)

{   var i;

    if (isEmpty(s)) return false;

    // Search through string's characters one by one
    // until we find a non-alphanumeric 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 or letter.
        var c = s.charAt(i);

        if (! (isLetter(c) || isDigit(c) || c == ' ') )
        return false;
    }
return true;
}

                                                                
function isEmail (s)
{   
  if (isEmpty(s)) return false;
   
    // is s whitespace?
    if (isWhitespace(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;
}

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


function isInteger (s)

{   var i;

    if (isEmpty(s)) return false;

    // 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 isZIPCode (s)
{  
 if (isEmpty(s)) return false;
   return (isInteger(s) &&  (s.length == digitsInZIPCode1));
}