How to save a checkbox meta box in WordPress?

Question

I\'m trying to add a checkbox into my custom meta box in WordPress and I ran into a problem with saving it - whenever I check the checkbox and update the post/page, it comes

Answer 1

I had trouble with this previously and here is how I solved it.

First, creating the Checkbox.

ID);
    $sl_meta_box_sidebar = $custom["sl-meta-box-sidebar"][0]; 
?>

checked="checked" />  Check the Box.

Next, saving.