How to fill a multidimensional array with values in php

I am experimenting with datatables and php, and trying to get an example server side script working at https://www.datatables.net/examples/data_sources/server_side.html.

as part of this I need to create an array of arrays of the datatable columns that looks like:

$columns = array(
                  array( 'db' => 'first_name', 'dt' => 0 ),
                  array( 'db' => 'last_name',  'dt' => 1 ),
                  array( 'db' => 'position',   'dt' => 2 ),
                  array( 'db' => 'office',     'dt' => 3 ),

              );

I have an array:

$mytablescolumns = array('name1','name2', ... )

which I would like to iterate through producing a 2d array that looks like:

 $columns = array(
                  array( 'db' => 'name1', 'dt' => 0 ),
                  array( 'db' => 'name2',  'dt' => 1 ),

I've looked at http://php.net/manual/en/function.array-fill.php and http://php.net/manual/en/function.array-fill-keys.php , but I'm not sure if these will accomplish this since they appear to deal with 1D arrays. How can I accomplish this?

I think a simple foreach is the easiest:

$array = array();
foreach($mytablescolumns as $index => $column) {
  $array[] = array('db' => $column, 'dt' => $index);
}

print_r($array);

This will create a new array in the $array variable. If you want to modify the original array, you can use it this way:

foreach($mytablescolumns as $index => &$column) {
  $column = array('db' => $column, 'dt' => $index);
}

print_r($mytablescolumns);