get_category_by_slug() 返回类别对象或FALSE:

$cat1 = get_category_by_slug( \'cata\' );
print \'<pre>\' . htmlspecialchars( print_r( $cat1, TRUE ) ) . \'</pre>\';

结果：

stdClass Object
(
    [term_id] => 3
    [name] => Cat A
    [slug] => cata
    [term_group] => 0
    [term_taxonomy_id] => 3
    [taxonomy] => category
    [description] => 
    [parent] => 0
    [count] => 2
    [cat_ID] => 3
    [category_count] => 2
    [category_description] => 
    [cat_name] => Cat A
    [category_nicename] => cata
    [category_parent] => 0
)

因此，要获得一个ID数组，只需检查是否为每个slug获得了一个对象，然后添加term_id 到阵列：

$category__not_in = array();
$slugs            = array ( \'cata\', \'catdoesnotexist\' );
foreach ( $slugs as $slug )
{
    $cat = get_category_by_slug( $slug );
    $cat and $category__not_in[] = $cat->term_id;
}
$args = array (
    \'category__not_in\' => $category__not_in
);

与其硬编码脚本中的段塞，不如考虑添加term meta data 到类别。您将需要一个额外的查询来查找所有需要的术语，但您的脚本仍然可以重用。