code: public static function coordinateFromString($pCoordinateString)
      {
          if (preg_match('/^([$]?[A-Z]{1,3})([$]?\\d{1,7})$/', $pCoordinateString, $matches)) {
              return [$matches[1], $matches[2]];
          } elseif (self::coordinateIsRange($pCoordinateString)) {
              throw new Exception('Cell coordinate string can not be a range of cells');
          } elseif ($pCoordinateString == '') {
              throw new Exception('Cell coordinate can not be zero-length string');
          }
  
          throw new Exception('Invalid cell coordinate ' . $pCoordinateString);
      }
docs: Coordinate from string.
  
  @param string $pCoordinateString eg: 'A1'
  
  @throws Exception
  
  @return string[] Array containing column and row (indexes 0 and 1)