There is no way to create an array of a predefined size without also supplying values for the elements of that array.
The best way to initialize an array like that is array_fill. By far preferable over the various loop-and-insert solutions.
$my_array = array_fill(0, $size_of_the_array, $some_data);
Every position in the $my_array will contain $some_data.
The first zero in array_fill just indicates the index from where the array needs to be filled with the value.