What are the potential pitfalls of not properly submitting checkbox values in PHP forms and how can they be avoided?

When checkbox values are not properly submitted in PHP forms, it can lead to issues such as not being able to distinguish between checked and unchecked checkboxes or not receiving any values at all. To avoid this, make sure to include a hidden input field with the same name as the checkbox and a default value that represents the unchecked state. This way, even if the checkbox is not checked, the form will still submit a value for that checkbox.

<input type="hidden" name="checkbox_name" value="0">
<input type="checkbox" name="checkbox_name" value="1">