sub binarySearch   ### sample call: $returnValue = binarySearch($begin, $query, \@ArrayPtr);
{
  my ($begin, $query, $ArrayPtr);      ### begin = 1 or 0
  ($begin, $query, $ArrayPtr) = @_;
  my(@array) = @$ArrayPtr;

  ### Handling cases when query is out of bounds
  return 0 if ($query < $array[0] && $begin == 1);
  return $#array if ($query > $array[$#array] && $begin == 0);

  my ($left) = 0;
  my ($right) = $#array;
  my ($center);
  my ($prevCenter) = -1;
  while(1)
  {
    $center = int (($left + $right)/2 );
    if ($query == $array[$center])
    {
      if ($begin == 1)
      {
        while($center > 0 && $array[$center] == $array[$center-1])
          { $center =  $center - 1; }
      }
      else
      {
        while($center < $#array && $array[$center] == $array[$center+1])
          { $center =  $center + 1; }
      }
      undef @array;
      return $center;
    }
    if ($center == $prevCenter)
    {
      undef @array;
      return $right if ($begin == 1);
      return $right-1 if ($begin == 0);
    }
    $right = $center if ($query < $array[$center]);
    $left = $center if ($query > $array[$center]);
    $prevCenter = $center;
  }
}