Escape double quotes with variable inside HTML echo

For a variable inside a echo that contains HTML, where would I add slashes to escape the double quotes?

Example:

echo "<input type=\"hidden\" name=\"id\" value=".$row['id']." />";

This part:

value=".$row['id']."

Some tips on outputting HTML with PHP:

1. Use single quotes so that you don't have to escape the double quotes (when using echo),
2. Use htmlspecialchars() to properly escape any "rogue" values you may have.

Example using echo:

echo '<input type="hidden" name="id" value="', htmlspecialchars($row['id'], ENT_QUOTES, 'UTF-8'), '" />';

Or printf():

printf('<input type="hidden" name="id" value="%s" />', 
    htmlspecialchars($row['id'], ENT_QUOTES, 'UTF-8')
);

Or, in HTML mode:

?>
<input type="hidden" name="id" value="<?php echo htmlspecialchars($row['id'], ENT_QUOTES, 'UTF-8'); ?>" />
<?php