array_combine() expects parameter 2 to be array, string given in php

Question

Array
(
    [0] => tttt
    [1] => tttt
)

$terms_keys = array("terms");
$terms_array = array();
foreach ( array_map(null,$inv_terms) as $key => $value ) {
    $terms_array[] = array_combine($terms_keys, $value);
}

what is mistake done in my code ?

Answer 1

The $value param in the foreach is of course not an array its a scalar tttt, so you could make it into an array by doing [$value] in the combine

$terms_keys = array("terms");
$terms_array = array();
foreach ( array_map(null,$inv_terms) as $key => $value ) {
    $terms_array[] = array_combine($terms_keys, [$value]);
}

Or simplified as the array_map() does not achieve anything

$terms_keys = array("terms");
$terms_array = array();
foreach ( $inv_terms as $key => $value ) {
    $terms_array[] = array_combine($terms_keys, [$value]);
}

Answer 2

I don't understand how it could be advantageous to bloat your array structure with more depth, but generating the indexed array of associative arrays can be done without iterated function calls. Just push the values into their new deep location using square-brace pushing syntax in a body-less foreach loop.

Code: (Demo)

$inv_terms = ['tttt', 'tttt'];
$result = [];
foreach ($inv_terms as $result[]['terms']);
var_export($result);

Output:

array (
  0 => 
  array (
    'terms' => 'tttt',
  ),
  1 => 
  array (
    'terms' => 'tttt',
  ),
)