Class with static functions for PARAMETER VALIDATION (for example, for site security) 
 
 
     DEPENDENCIES:  None
 
 
     USAGE EXAMPLE:
    
        parameterValidation::validateInteger($myValue)

    public static function validatePositiveInteger($arg)
    /* Check if the given argument is a positive, non-zero integer, (or a string representing such an integer.)  
       Return true if the check succeeded, or false if not
     */

    
    
    public static function validateInteger($arg)
    /*     Check if the given argument is a positive integer (or a string representing such an integer.)  
        Return true if the check succeeded, or false if not
     */

    
    
    public static function validateNumeric($arg)
    /*     Check if the given argument is a numeric quantity. 
        Return true if the check succeeded, or false if not
     */

    
    
    public static function validateAlphanumeric($arg)
    /* Verify that the given argument is alphanumeric
     */

 

   
    public static function validateAlphanumericOrBlank($arg)
    /* Verify that the given argument is alphanumeric or blank
     */

    
    public static function validateAlphanumericOrUnderscore($arg)
    /* Verify that the given argument is alphanumeric or underscore
     */

    
    public static function validateUsername($user)       
    /* Verify that the given username (which might also be an email address or an ID) is drawn from the allowed character set 
     */

    
    public static function validatePassword($pass)    
    /* Verify that the given password is drawn from the allowed character set 
     */

    
      
    public static function validatePattern($string, $pattern, $debug = false)
    /*     Check the given string value against the specified RegEx pattern.
        If it matches (or if it's an empty string), return true; otherwise print out the given error message (details based on the $stage flag) and return false.
        EXAMPLE:    validatePattern($ID, "/^[0-9]+$/", "ID must be an integer.  Value provided: “$ID”", true);
     */