How to print list using hierarchical data structure?

Question

When I run this code:

foreach ($tree as $node) {
    echo str_repeat(\' \', $node->tree_depth * 4) . $node->id . PHP_EOL;
}

I get well fo

Answer 1

Try this algorithm:

$tree = array(
    array('Food', 0),
    array('Fruit', 1),
    array('Red', 2),
    array('Cherry', 3),
    array('Strawberry', 3),
    array('Cool', 4),
    array('Not cool', 4),
    array('Yellow', 2),
    array('Banana', 3),
    array('Meat', 0),
    array('Beef', 1),
    array('Pork', 1),
);

$depth = -1;
$flag = false;
foreach ($tree as $row) {
    while ($row[1] > $depth) {
        echo "
\n", "
";
        $flag = false;
        $depth++;
    }
    while ($row[1] < $depth) {
        echo "
\n", "
\n";
        $depth--;
    }
    if ($flag) {
        echo "