Linked List

This is a simple doubly linked list implementation for use in C projects.

Functionality

ll_new(void)

This function initializes a management node for a linked list and returns a pointer to the node.

ll_destroy(linked_list_t * ll)

This function destroys the linked list and all associated data. All data pointers supplied are freed upon calling this function.

ll_size(linked_list_t * ll)

This function returns the number of nodes in the linked list. This can be retrieved by calling the linked_list_t.size parameter of the linked list management node structure.

ll_sort(linked_list_t *ll, int (*compare_function)(void *first_data, void *second_data))

This function sorts the provided linked list in place using quick sort with the supplied compare function. The compare function MUST return an integer and accept two void pointers as passed parameters. The compare function must return a negative number if the second parameter is larger than the first, a zero if equal or a positive number if the first parameter is larger than the second.

ll_push_tail(linked_list_t * ll, void * data)

This function pushes the data pointer onto the tail of the provided linked list and adjusts the tail pointer.

ll_push_head(linked_list_t * ll, void * data)

This function pushes the data pointer onto the head of the provided linked list and adjusts the head pointer.

ll_push_after(linked_list_t *ll, void *data, bool (*compare_function)(void *cmd_data))

This function will push after the specified node based on the compare function.

ll_push_before(linked_list_t *ll, void *data, bool (*compare_function)(void *cmd_data))

This function will push before the specified node based on the compare function.

ll_push_at_index(linked_list_t *ll, void *data, int index)

This function will push at the specified index and adjust the list.

ll_pop_head(linked_list_t * ll)

This function returns the data of the head node and adjusts the head pointer to point at the next node.

ll_pop_tail(linked_list_t * ll)

This function returns the data of the tail node and adjusts the tail pointer to point at the previous node.

ll_pop_by(linked_list_t * ll, bool (*compare_function)(void *cmd_data))

This function returns the data of the first node that a true is returned from the supplied compare function. The compare function MUST return a boolean and accept a void pointer as a passed parameter. The node is removed from the list and the list is adjusted.

ll_pop_by_index(linked_list_t * ll, int index)

This function returns the specified node based on the provided index.

• This is based on a 0 index (0 is head).
• Optionally, can use negative indexing (-1 is tail) to traverse backwards.

ll_print_list(linked_list_t * ll, (optionally) bool reversed)

This function prints for each node:

• The address of the node,
• The address of the data,
• The address of the previous node,
• The address of the next node

The reversed parameter is option, but adding supplying reversed as true will print the list in reverse.

This is useful for debugging.

Version History

v1.0:

• Initial creation of doubly linked list with head and tail pointers in management node.
• Can push and pop from either end of the linked list.
• Can destroy entire linked list, including all data supplied to the list.
• Can iterate through list to find a specific node based on its data.