1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 | #include <stdio.h>
#include <stdlib.h>
#include <assert.h>
#pragma pack(1) // OPTIONAL: Makes the Valgrind messages more predictable
struct Node {
int value; // 4 bytes (on our platform)
struct Node* next; // 8 bytes (on our platform)
}; // 12 bytes for a whole node (on our platform)
void print_linked_list_of_ints(struct Node* head) {
for(struct Node* curr = head; curr != NULL; curr = curr -> next) {
printf("curr -> value == %d\n", curr -> value);
}
}
// Let's make this right... STILL NOT QUITE
void append(int value, struct Node** a_head, struct Node** a_tail) {
assert( (*a_tail == NULL) == (*a_head == NULL) ); // If head is NULL,
// tail must be, too.
// create_list_node(value)
struct Node* new_node = malloc(sizeof(*new_node));
new_node -> value = value;
new_node -> next = NULL;
if(*a_tail == NULL) { // If list is empty
*a_head = new_node;
}
else { // Not empty....
(*a_tail) -> next = new_node;
}
*a_tail = new_node;
}
void destroy_list(struct Node** a_head, struct Node** a_tail) {
while(*a_head != NULL) { // NOT: while(*a_head) { … }
struct Node* victim = *a_head;
*a_head = (*a_head) -> next;
free(victim); // You would think that freeing the victim would
} // let it get away. This victim will not escape.
*a_head = NULL;
*a_tail = NULL;
}
int main(int argc, char* argv[]) {
struct Node* head = NULL;
struct Node* tail = NULL;
append(10, &head, &tail);
append(11, &head, &tail);
append(12, &head, &tail);
append(13, &head, &tail);
append(14, &head, &tail); // Vim tip: Ctrl-A to add 1 to a number
append(15, &head, &tail); // Vim tip: Don't try Ctrl-S.
print_linked_list_of_ints(head);
destroy_list(&head, &tail);
// TODO: Free memory before we exit.
return EXIT_SUCCESS;
}
/* vim: set tabstop=4 shiftwidth=4 fileencoding=utf-8 noexpandtab: */
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