// variable declarations
var reWhitespace = /^\s+$/
var reAlphabetic = /^[a-zA-Z]+$/
var reAlphanumeric = /^[a-zA-Z0-9]+$/
var reInteger = /^\d+$/
var reDouble = /^\d+.\d+$/
var reEmail = /^[a-zA-Z][\w\.-]*[a-zA-Z0-9]@[a-zA-Z0-9][\w\.-]*[a-zA-Z0-9]\.[a-zA-Z][a-zA-Z\.]*[a-zA-Z]$/


/***********************
String
***********************/

// true: empty
// false: not empty
function isEmpty(s){
	return ((s == "") || (s.length == 0))
}
function isAlphabetic(s){
		return (reWhitespace.test(s)||reAlphabetic.test(s));
}
function isAlphaNumeric(s){
		return reAlphanumeric.test(s);
}

function isInteger(s){
  		return reInteger.test(s);
}

function isDouble(s){	
 		return reInteger.test(s) || reDouble.test(s);
}

function isValidEmail(s){
  		return reEmail.test(s);
}