Create a Pagination with PHP

Example of a pager (pagination) on php:

function showpager($currentIndex = 0, $buttons = 5, $totalPages = 50) {
  $currentPage = $lowerLimit = $upperLimit = min($currentIndex, $totalPages);
  //Search boundaries
  for ($b = 0; $b < $buttons && $b < $totalPages;) {
    if ($lowerLimit > 0) {
      $lowerLimit--;
      $b++;
    }
    if ($b < $buttons && $upperLimit < $totalPages) {
      $upperLimit++;
      $b++;
    }
  }
  //Do output to a html element
  for ($i = $lowerLimit; $i < $upperLimit; $i++) {
    if ($i == $currentPage) {
      echo ' [' . $i . '] ';
    }
    else {
      echo ' <a href="#">[<em>' . $i . '</em>]</a> ';
    }
  }
}

For Tests :
for ($i = 0; $i < 51; $i++) {
  echo "<br> $i : ";
  showpager($i);
}