List all the categories with or without post

Question

I have a simple question!

I'm showing the WP categories with this code :

wp_dropdown_categories(
    array (
        'orderby' => 'name',
        // ID of the already selected category:
        'selected' => 4,
        // If no category is selected:
        'show_option_none' => 'Choose one'
    )
);

Problem is that how can i list every category that have post or not. specially the code just shows the categories that have post , but i want to show ALL categories .

How can i change that code ?

ALso , it's important to get the HTML output like this :

<select name='cat' id='cat' class='postform' >
    <option value='-1'>Choose one</option>
    <option class="level-0" value="4" selected="selected">Animals</option>
    <option class="level-0" value="6">Hyperbolica</option>
    <option class="level-0" value="5">Nonsense</option>
    <option class="level-0" value="1">Uncategorized</option>
</select>

Answer 1

Problem is solved.

Just need to add 'hide_empty' => false, to the array.

Like this :

wp_dropdown_categories(
    array (
        'orderby' => 'name',
        // ID of the already selected category:
        'selected' => 4,
        'hide_empty' => false,
        // If no category is selected:
        'show_option_none' => 'Choose one'
    )
);