致命错误：未捕获错误：无法使用字符串偏移量作为数组

Question

A custom field extension is added to a blog plugin causing this error "Fatal error: Uncaught Error: Cannot use string offset as an array" I'm using PHP7 I tried to use array_key_exists() but this didn't solve the error it accidentally disabled the extension

public function getCustomFields()
  {
    $cfData = getXML(BLOGCUSTOMFIELDS);
    $cf = array('options' => '', 'main' => '');
    $count_options = 0;
    $count_main = 0;
    $count_opt = 0;
    foreach($cfData->item as $custom_field)
    {
      if($custom_field->area == 'options')
      {
        $cf['options'][$count_options]['key'] = (string) $custom_field->desc;
        $cf['options'][$count_options]['label'] = (string) $custom_field->label;
        $cf['options'][$count_options]['type'] = (string) $custom_field->type;
        $cf['options'][$count_options]['value'] = (string) $custom_field->value;
        if ($custom_field->type == "dropdown") 
        {
          $count_opt = 0;
          $cf['options'][$count_options]['options'] = array();
          foreach ($custom_field->option as $option) 
          {
            $cf['options'][$count_options]['options'][] = (string) $option;
            $count_opt++;
          }
        }
        $count_options++;
      }
      elseif($custom_field->area == 'main')
      {
        $cf['main'][$count_main]['key'] = (string) $custom_field->desc;
        $cf['main'][$count_main]['label'] = (string) $custom_field->label;
        $cf['main'][$count_main]['type'] = (string) $custom_field->type;
        $cf['main'][$count_main]['value'] = (string) $custom_field->value;
        if ($custom_field->type == "dropdown") 
        {
          $count_opt = 0;
          $cf['main'][$count_main]['options'] = array();
          foreach ($custom_field->option as $option) 
          {
            $cf['main'][$count_main]['options'][] = (string) $option;
            $count_opt++;
          }
        }
        $count_main++;
      }
    }
    return $cf;
  }

According to the error it's referring to

$cf = array('options' => '', 'main' => '');

Your help is much appreciated.

EDIT: Dumping the XML File

object(SimpleXMLExtended)#483 (1) { ["item"]=> array(8) { [0]=> object(SimpleXMLExtended)#484 (4) { ["area"]=> string(7) "options" ["desc"]=> string(4) "slug" ["label"]=> string(8) "Slug/URL" ["type"]=> string(4) "text" } [1]=> object(SimpleXMLExtended)#485 (4) { ["area"]=> string(7) "options" ["desc"]=> string(4) "tags" ["label"]=> string(32) "Tags (separate tags with commas)" ["type"]=> string(4) "text" } [2]=> object(SimpleXMLExtended)#486 (4) { ["area"]=> string(7) "options" ["desc"]=> string(4) "date" ["label"]=> string(25) "Publish date (any format)" ["type"]=> string(4) "text" } [3]=> object(SimpleXMLExtended)#487 (4) { ["area"]=> string(7) "options" ["desc"]=> string(8) "category" ["label"]=> string(30) "Assign This Post To A Category" ["type"]=> string(8) "dropdown" } [4]=> object(SimpleXMLExtended)#488 (4) { ["area"]=> string(7) "options" ["desc"]=> string(6) "author" ["label"]=> string(14) "Author's Name:" ["type"]=> string(4) "text" } [5]=> object(SimpleXMLExtended)#489 (4) { ["area"]=> string(7) "options" ["desc"]=> string(7) "private" ["label"]=> string(15) "Post is private" ["type"]=> string(8) "checkbox" } [6]=> object(SimpleXMLExtended)#490 (4) { ["area"]=> string(4) "main" ["desc"]=> string(5) "title" ["label"]=> object(SimpleXMLExtended)#492 (0) { } ["type"]=> string(5) "title" } [7]=> object(SimpleXMLExtended)#491 (4) { ["area"]=> string(4) "main" ["desc"]=> string(7) "content" ["label"]=> object(SimpleXMLExtended)#493 (0) { } ["type"]=> string(8) "textarea" } } }

Answer 1

Change
$cf = array('options' => '', 'main' => '');
to
$cf = array('options' => array(), 'main' => array());

The error says that

Fatal error: Uncaught Error: Cannot use string offset as an array

Your code is wrong because you are trying add new key into $cf['options'] but it is string and not array

$cf['options'][$count_options] .....

Answer 2

Since the release PHP 7.1+, is not more possible to initialize an array witrh As of PHP 7.1.0, applying the empty index operator on a string throws a fatal error. Formerly, the string was silently converted to an array.