How to improve the for code?

Question

PHP

There is another error in the code where the if function begins, I can not understand what the problem is.

$figures = preg_split("-[\W]-u", "1 2 3 4");
$bas = $i = [];

for ($a = 0; $a <= count($figures); $a++) {
    for ($b = 0; $b < $a; $b++) {
        $c = array(implode(' ', array_slice($figures, $b, count($figures) - $a + 1)));

        if (!isset($i[$c])) {
            $i[$c] = array_push($bas, $c);
        }
    }
}

print_r($bas);

you need to complete the code to such a state

Array
(
    [0] => Array
        (
            [0] => 1 2 3 4
        )

    [1] => Array
        (
            [0] => 1 2 3
      [1] => 4
        )

    [2] => Array
        (
      [0] => 1
            [1] => 2 3 4
        )

    [3] => Array
        (
            [0] => 1 2
      [1] => 3 4
        )

    [4] => Array
        (
      [0] => 1
            [1] => 2 3
      [2] => 4
        )

    [5] => Array
        (
      [0] => 1 2
            [1] => 3 4
        )

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

    [7] => Array
        (
            [0] => 2
        )

    [8] => Array
        (
            [0] => 3
        )

    [9] => Array
        (
            [0] => 4
        )

)

Answer 1

First, replace single-letter variables with normal ones.

Answer 2

How to collect a multilevel array?

Answer 3

Take the debugger in your hands and do everything line by line, you will most likely find an error much faster than strangers will delve into your code and fix it.
You can get by with a low-budget version of the debugger - output all values ​​to standard output or somewhere else.

Answer 4

$i[$c]
Are you pushing an array into the key?

Arrays (type array) and objects (type object) cannot be used as keys. Using it this way will generate a warning: Illegal offset type.

Answer 5

The issue has long been resolved.