ListTail

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API Reference

ListTail

Description

Direct O(1) reference to the tail node, or NULL when the list is empty. Unlike ListNodeEnd (which aborts on empty), this is safe to call on an empty list.

Parameters

Name	Direction	Description
`l`	in	List to query.

Success

Returns the tail-node pointer.

Failure

Returns NULL when the list is empty. The list is not modified.

Usage example (Cross-references)

Usage examples (Cross-references)

In Ops.c:101:

        ListClear(&list);
    
        bool result = (ListLen(&list) == 0) && (ListHead(&list) == NULL) && (ListTail(&list) == NULL);
    
        ListPushBackR(&list, 9);

In Ops.c:151:

        ListReverse(&singleton);
    
        bool result = (ListLen(&empty) == 0) && (ListHead(&empty) == NULL) && (ListTail(&empty) == NULL);
        result      = result && list_matches(GENERIC_LIST(&singleton), (const int[]) {42}, 1);

In Ops.c:176:

        ListClear(&list);
        result = result && (g_copy_deinit_count == 2);
        result = result && (ListLen(&list) == 0) && (ListHead(&list) == NULL) && (ListTail(&list) == NULL);
    
        ListPushBackR(&list, 9);

In Init.c:108:

    
        result = result && (g_copy_deinit_count == 2);
        result = result && (ListHead(&list) == NULL) && (ListTail(&list) == NULL) && (ListLen(&list) == 0);
        // Verifying ListDeinit clears the hook fields.
        result = result && (ListCopyInit(&list) == NULL) && (ListCopyDeinit(&list) == NULL);

In Insert.c:198:

        bool result = (g_copy_init_count == 2);
        result      = result && list_matches(GENERIC_LIST(&dest), (const int[]) {1003, 1004}, 2);
        result      = result && (ListLen(&src) == 0) && (ListHead(&src) == NULL) && (ListTail(&src) == NULL);
        result      = result && (ListCopyInit(&src) == tracked_copy_init) && (ListCopyDeinit(&src) == tracked_copy_deinit);

In Insert.c:242:

    
        bool result = list_matches(GENERIC_LIST(&dest_l), (const int[]) {1, 2, 3, 4}, 4);
        result      = result && (ListLen(&src_l) == 0) && (ListHead(&src_l) == NULL) && (ListTail(&src_l) == NULL);
        result      = result && list_matches(GENERIC_LIST(&dest_r), (const int[]) {1, 2, 3, 4}, 4);
        result      = result && list_matches(GENERIC_LIST(&src_r), (const int[]) {3, 4}, 2);

In Insert.c:246:

        result      = result && list_matches(GENERIC_LIST(&src_r), (const int[]) {3, 4}, 2);
        result      = result && list_matches(GENERIC_LIST(&dest_a), (const int[]) {5, 6}, 2);
        result      = result && (ListLen(&src_a) == 0) && (ListHead(&src_a) == NULL) && (ListTail(&src_a) == NULL);
    
        ListDeinit(&dest_l);

In Type.c:29:

        // checks; no public accessor exposes it, so the layout test reads it
        // directly to confirm ListInit planted the right value.
        bool result = (ListHead(&list) == NULL) && (ListTail(&list) == NULL) && (ListCopyInit(&list) == NULL) &&
                      (ListCopyDeinit(&list) == NULL) && (ListLen(&list) == 0) && MAGIC_MATCHES(list.__magic, LIST_MAGIC);

In Remove.c:70:

        result = result && list_matches(GENERIC_LIST(&list), (const int[]) {30}, 1);
        result = result && ListHead(&list) && ListNodeData(ListHead(&list)) && (*ListNodeData(ListHead(&list)) == 30);
        result = result && ListTail(&list) && ListNodeData(ListTail(&list)) && (*ListNodeData(ListTail(&list)) == 30);
    
        ListDeinit(&list);

In Remove.c:104:

    
        ListDeleteRange(&list, 0, 2);
        result = result && (ListLen(&list) == 0) && (ListHead(&list) == NULL) && (ListTail(&list) == NULL);
    
        ListDeinit(&list);

In Remove.c:136:

        result = result && list_matches(GENERIC_LIST(&list), (const int[]) {3, 4}, 2);
        result = result && ListHead(&list) && ListNodeData(ListHead(&list)) && (*ListNodeData(ListHead(&list)) == 3);
        result = result && ListTail(&list) && ListNodeData(ListTail(&list)) && (*ListNodeData(ListTail(&list)) == 4);
    
        ListDeinit(&list);

In Remove.c:158:

    
        bool result = (removed[0] == 7) && (removed[1] == 8) && (removed[2] == 9);
        result      = result && (ListLen(&list) == 0) && (ListHead(&list) == NULL) && (ListTail(&list) == NULL);
    
        ListDeinit(&list);

In Remove.c:197:

        ListClear(&list);
        result = result && (g_copy_deinit_count == 2);
        result = result && (ListLen(&list) == 0) && (ListHead(&list) == NULL) && (ListTail(&list) == NULL);
    
        ListDeinit(&list);

In Access.c:80:

        result = result && (ListLen(&list) == 0);
        result = result && ListEmpty(&list);
        result = result && (ListHead(&list) == NULL) && (ListTail(&list) == NULL);
    
        ListPushBackR(&list, 30);

Last updated on July 1, 2026

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