如何获取包含特定子字符串的数组的键？

This is my array:-

$ header_menu = array(
    ['category'] => array(
                    'id'    => 1,
                    'title' => 'Test Apple',
                    'slug'  => 'category'
                    ),
    ['how-to-do'] => array(
                    'id'    => 1,
                    'title' => 'How to do',
                    'slug'  => 'how-to-do'
                    )               
)

The array is formed dynamically based on the data saved in the table. Due to that, sometimes the key can be 'category', sometimes it can be 'categories', based on what the admin has saved in the DB.

I need to fetch the key which has the substring 'categor', because this sequence of alphabets is present both in 'category' & 'categories'. By the following code, I can check if the 'categor' substring is present in any of the key or not:-

if (preg_grep('/^categor/', array_keys($header_menu)))
{

}

One way is to run a loop like this:-

foreach($header_menu as $key => $row)
{
   if(strpos($key, 'categor') !== false)
   {
       $catKey = $key;
   } 
}

However, I don't want to run a loop. Is there any other way to fetch the matching key?

You can use preg_grep if you do not want to loop through with array_keys() to get every key of your array and find all key matching given pattern.

$matchingKeys = array_keys($header_menu);
$matchingKeys = preg_grep('/'.'categor'.'\.\d/i', $matchingKeys);

If you know that you have only two options category/categories , you can check if one of this fields exists in array:

if (isset($header_menu['category'])) {
    $key = 'category';
} elseif (isset($header_menu['categories'])) {
    $key = 'categories';
}

switch variation which allows many options:

switch (true) {
    case isset($header_menu['category']):
        $key = 'category';
        break;

    case isset($header_menu['categories']):
        $key = 'categories';
        break;
}