【PHP】PHP导出Excel所需要的表头上方的字母超过26位的解决方法

    /**
     * @Author: 小破孩嫩
     * @Email: 3584685883@qq.com
     * @Time: 2020/12/23 16:08
     * @param int $column_num
     * @return mixed
     * @Description：获取表格列数的字母
     */
    public function getMaxColumn(int $column_num)
    {
        try{
            if(empty($column_num)){
                throw new Exception('column_num:列数为空~');
            }
            if(!is_int($column_num)){
                throw new Exception('column_num:参数类型错误~');
            }
            if($column_num > 26*26 || $column_num < 0){
                throw new Exception('最大列数：676列,最小列数：1列');
            }
            $column_word = ['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'];
            //生成循环次数
            $num = ceil($column_num/26);
            for($c = 0; $c < $num; $c++) {
                $first_word = $column_word[$c-1];
                foreach($column_word as $key => $val){
                    if($c >= 1){
                        $word = $first_word.$column_word[$key];
                    }else{
                        $word = $column_word[$key];
                    }
                    $column[] = $word;
                }
            }
            for($a = 0; $a < $column_num; $a++){
                $new_column[] = $column[$a];
            }
            return $new_column;
        }catch (Exception $e){
            returnResponse(100,$e->getMessage());
        }
    }