CMPSC 311, Linked Lists in C

Reading

• C:ARM, Sec. 5.3, Pointer Types.  (review)
  
• C:ARM, Sec. 5.6, Structure Types.




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/* CMPSC 311, Linked List, demo version 1a
 *   data structures
 *   function prototypes
 *   functions
 *   test program
 */

struct node {
};

struct list {
};

  struct list demo;

  list_insert(demo, node_create(“foo”));

  list_print(demo);

  // What’s wrong here?  [discussion]



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/* CMPSC 311, Linked List, demo version 1b
 *   data structures
 *   function prototypes
 *   functions
 *   test program
 *
 * The symbol *** represents code omitted for now,
 *   to be supplied later.
 */

// data structures

struct node {
};

struct list {
};

// function prototypes

struct node *node_create(char *name);
struct list *list_create(char *name);
void list_insert(struct list *list, struct node *node);
void list_print(struct list *list);

// functions

// test program

// statically-allocated list header (global)

struct list demo1 = ***;

int main(int argc, char *argv[])
{
  // automatically-allocated list header (local)

  struct list demo2 = ***;

  for (int i = 0; i < argc; i++)
    {
      list_insert(&demo2, node_create(argv[i]));
    }

  list_print(&demo2);

  // dynamically-allocated list header (local pointer)

  struct list *demo3 = list_create("demo3");

  for (int i = 0; i < argc; i++)
    {
      list_insert(demo3, node_create(argv[i]));
    }

  list_print(demo3);

  return 0;
}

// Draw a map of the memory, and indicate where the lists and nodes are.

// What’s wrong here?  [discussion]



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/* CMPSC 311, Linked List, demo version 1c
 */

// data structures

struct node {
  struct node *next;
  char *name;
  void *data;
};

struct list {
  struct node *head;
  char *name;
};

// This requires C99.
#define NODE_INIT { .next = NULL, .name = "", .data = NULL }
#define NODE_EMPTY (struct node) NODE_INIT
#define LIST_INIT { .head = NULL, .name = "" }
#define LIST_EMPTY (struct list) LIST_INIT

// example
struct list demo = LIST_INIT;
demo = LIST_EMPTY;

// function prototypes

struct node *node_create(char *name);
struct node *list_create(char *name);

// functions

struct node *node_create(char *name)
{
  struct node *ptr = malloc(sizeof(struct node));

  ptr->next = NULL;
  ptr->name = name;
  ptr->data = NULL;

  return ptr;
}

struct list *list_create(char *name)
{
  struct list *ptr = malloc(sizeof(struct list));

  ptr->head = NULL;
  ptr->name = name;

  return ptr;
}

// What’s wrong here?  [discussion]



---


/* CMPSC 311, Linked List, demo version 1d
 */

// function prototypes

void list_init(struct list *list, char *name);
void list_make_empty(struct list *list);

// functions

void list_init(struct list *list, char *name)
{
  list_make_empty(list);
  list->name = name;
}

void list_make_empty(struct list *list)
{
  ***
}



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Some different designs

• One struct type only
• 
  

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Last revised, 28 July 2008