PHP - nested Arrays

From this global variable:

echo '<pre>';
print_r($wp_registered_sidebars);
echo '</pre>';

I'm getting output like this:

Array
(
    [sidebar-1] => Array
        (
            [name] => Main Sidebar
            [id] => sidebar-1
            [description] => text
            [before_widget] => 
            [after_widget] => 
            [before_title] => 
            [after_title] =>
        )

    [sidebar-2] => Array
        (
            [name] => Footer Sidebar 1
            [id] => sidebar-2
            [des开发者_StackOverflow中文版cription] => text
            [before_widget] => 
            [after_widget] => 
            [before_title] => 
            [after_title] =>
        )

    [sidebar-3] => Array
        (
            [name] => Footer Sidebar 2
            [id] => sidebar-3
            [description] => text
            [before_widget] => 
            [after_widget] => 
            [before_title] => 
            [after_title] =>
        )
)

I never know how many sidebars there are and how they are named.

Is there a way of:

• listing all sidebrs IDs only - sidebar-1, sidebar-2, sidebar-3,
• listing all sidebar names only - Main Sidebar, Footer Sidebar 1, Footer Sidebar 2,

Thank you!

$resultSlideBars = array();
foreach($wp_registered_sidebars as $slidebars)
{
   $resultSlideBars[$slidebars['id']] = $slidebars['name'];    // will store array as array(id => name

}

// ids 
echo implode(' ', array_keys($resultSlideBars)); 
echo implode(' ', $resultSlideBars);   // echo names

or

foreach($wp_registered_sidebars as $slidebars)
{
   echo $slidebars['id'];      // echo id 
   echo $slidebars['name'];    // echo name
}

foreach(array_keys($wp_registered_sidebars) as $sidebarID) {
    echo $sidebarID;
}

foreach($wp_registered_sidebars as $sidebar) {
    echo $sidebar['name'];
}

$sidebarIds = array_keys($wp_registered_sidebars);

$sideBarNames = array();
foreach($wp_registered_sidebars as $row)
{
  $sideBarNames[] = $row['name'];
}

foreach ($wp_registered_sidebars as $key => $sidebars) {
    echo "sidebar id" . $key;
    echo "sidebar name " . $sidebar['name'];
}