protected function getUsedColumns()
    {
        if (strlen($this->maxColumn) == 2) {
            $usedColumns = range('A', 'Z');
            $max = $this->maxColumn[0];
            $upperRange = range('A', $max);
            foreach ($upperRange as $x) {
                $end = $max == $x ? $this->maxColumn[1] : 'Z';

                foreach (range('A', $end) as $y) {
                    $usedColumns[] = sprintf('%s%s', $x, $y);
                };
            }
        } else {
            $usedColumns = range('A', $this->maxColumn);
        }

        return $usedColumns;
    }
protected function getUsedColumns()
    {
        if (strlen($this->maxColumn) == 2) {
            $usedColumns = range('A', 'Z');
            $max = $this->maxColumn[0];
            $upperRange = range('A', $max);
            foreach ($upperRange as $x) {
                $end = $max == $x ? $this->maxColumn[1] : 'Z';

                foreach (range('A', $end) as $y) {
                    $usedColumns[] = sprintf('%s%s', $x, $y);
                };
            }
        } else {
            $usedColumns = range('A', $this->maxColumn);
        }

        return $usedColumns;
    }
protected function getUsedColumns ( ) { if ( strlen ( $ this -> maxColumn ) == 2 ) { $ usedColumns = range ( 'A' , 'Z' ) ; $ max = $ this -> maxColumn [ 0 ] ; $ upperRange = range ( 'A' , $ max ) ; foreach ( $ upperRange as $ x ) { $ end = $ max == $ x ? $ this -> maxColumn [ 1 ] : 'Z' ; foreach ( range ( 'A' , $ end ) as $ y ) { $ usedColumns [ ] = sprintf ( '%s%s' , $ x , $ y ) ; } ; } } else { $ usedColumns = range ( 'A' , $ this -> maxColumn ) ; } return $ usedColumns ; }
Get all used columns, based on the maxColumn

@return array
Get all used columns based on the maxColumn