/*
  ============================================================================
  This function simply returns a string of random digits in any given base
  from 2 to 36.

  It makes use of the new Random_Int() function of PHP 7+

  ARGUMENTS
  NumDigits = Number of digits to generate (at least 1).
              Default = 1

  Base = Base of number system used for randomized digits (2 to 36).
         Default = 10

  FALSE is returned if either argument is non-numeric.

  NO DEPENDENCIES
  ============================================================================
*/

   function Random_Digits ($NumDigits=1, $Base=10)
{
   $N = trim($NumDigits);
   $B = trim($Base);

// Error if either argument is non-numeric.
   if (!Is_Numeric($N) or !Is_Numeric($B))
  {
   return FALSE;
  }
// Set to minimum of 1 digit if N < 1.
   if ($N < 1) {$N = 1;}

// Truncate both arguments
// to positive integers.
   $N = floor(abs($N));
   $B = floor(abs($B));

// Error if base is out of legal range from 2 to 36.
   if ($B < 2 or $B > 36) {return FALSE;}

// Define digits used for bases 2 to 36.
   $DIGITS = substr('0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ', 0, $B);

// Execute loop to generate the randomized digits.
   $DigitsString = '';

   for($n=0;   $n < $N;   $n++)
  {
   $DigitsString .= substr($DIGITS, Random_Int(0, $B-1), 1);
  }
   return "$DigitsString";

} // End of  Random_Digits(...)