How to display a category tree?

 <?php $shop_categories = [ [ 'title' => 'Компьютеры', 'children' => [ [ 'title' => 'Ноутбуки', ], [ 'title' => 'Моноблоки', ], [ 'title' => 'Системные блоки', 'children' => [ [ 'title' => 'Tower', ], [ 'title' => 'Mini Tower', ] ] ] ] ], [ 'title' => 'Бытовая техника', 'children' => [ [ 'title' => 'Пылесосы', ], [ 'title' => 'Холодильники', ] ] ] ]; function write_title($title, $level) { for($i = 0; $i< $level; ++$i) { echo '--'; } echo $title.PHP_EOL; } function print_tree(array $data, $level = 0) { foreach($data as $node) { write_title($node['title'], $level); if(array_key_exists('children', $node)) { print_tree($node['children'], $level + 1); } } } print_tree($shop_categories, 0); 

result