Alphanumeric Increment a string in PHP (To a certain length)

Question

I need to generate a sequence (or function to get a \"next id\") with an alphanumeric incrementor.

The length of the string must be defineable, and the Characters mu

Answer 1

function formatPackageNumber($input)
 { 
  //$input = $_GET['number'];

  $alpha_array = array("A", "B" , "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z");
  $number_array = array("0", "1" , "2", "3", "4", "5", "6", "7", "8", "9");
  $output = "";

  for($i=0; $i<=5; $i++){
     if($i>=4) {
      $divisor = pow(26,$i-3)*pow(10,3);
    } else {
      $divisor = pow(10,$i);
    }
    $pos = floor($input/$divisor);

    if($i>=3) {
      $digit = $pos%26;
      $output .= $alpha_array[$digit];
    } else {
      $digit = $pos%10 ;
      $output .= $number_array[$digit];
    }
  } 
return  strrev($output);

}