获取二维数组中的元素(PHP 5.5新增函数),兼容低版本处理

 function i_array_column($input, $columnKey, $indexKey=null){
        if(!function_exists('array_column')){
            $columnKeyIsNumber  = (is_numeric($columnKey))?true:false;
            $indexKeyIsNull            = (is_null($indexKey))?true :false;
            $indexKeyIsNumber     = (is_numeric($indexKey))?true:false;
            $result                         = array();
            foreach((array)$input as $key=>$row){
                if($columnKeyIsNumber){
                    $tmp= array_slice($row, $columnKey, 1);
                    $tmp= (is_array($tmp) && !empty($tmp))?current($tmp):null;
                }else{
                    $tmp= isset($row[$columnKey])?$row[$columnKey]:null;
                }
                if(!$indexKeyIsNull){
                    if($indexKeyIsNumber){
                      $key = array_slice($row, $indexKey, 1);
                      $key = (is_array($key) && !empty($key))?current($key):null;
                      $key = is_null($key)?0:$key;
                    }else{
                      $key = isset($row[$indexKey])?$row[$indexKey]:0;
                    }
                }
                $result[$key] = $tmp;
            }
            return $result;
        }else{
            return array_column($input, $columnKey, $indexKey);
        }
    }