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 60 61 62 63 64 65 66 67 68 69 70 71 | #include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <assert.h>
typedef struct _Node {
int* a_value; // 8 bytes
struct _Node* next; // 8 bytes
} Node; // 16 bytes for a Node object (ignoring padding)
void append(int* a_value, Node** a_head, Node** a_tail) {
// Create (allocate and initialize) the new node, which will become the tail.
Node* new_tail = malloc(sizeof(*new_tail));
*new_tail = (Node) { .a_value = a_value, .next = NULL }; // compound literal (syntax)
if(*a_tail == NULL) { // if list is empty
*a_head = new_tail;
}
else { // List is not empty, so connect new_tail to the old tail.
(*a_tail) -> next = new_tail;
}
// Connect the tail of the list to new_tail.
*a_tail = new_tail;
assert(*a_head != NULL && *a_tail != NULL); // Sanity check: list is not empty anymore
}
void destroy_list(Node** a_head, Node** a_tail) {
while(*a_head != NULL) { // as long as list is not empty
Node* new_head = (*a_head) -> next;
free(*a_head);
*a_head = new_head; // Now head is the next node in the list.
}
*a_tail = NULL;
}
void print_list(Node* head) {
// Step through the linked list, printing each value.
for(Node* curr = head; curr != NULL; curr = curr -> next) {
printf("[%d]→", *(curr -> a_value));
}
printf("NULL\n");
}
int main(int argc, char* argv[]) {
// size==0
Node* head = NULL;
Node* tail = NULL; // You don't always need to keep track of the tail. It helps here.
// size==1
int n1 = 10;
append(&n1, &head, &tail); // Pass address of head and tail so they can be modified.
assert(head != NULL && tail != NULL); // Sanity check: list is no longer empty
assert(head == tail); // Sanity check: head and tail are same (size==1)
assert(*(head -> a_value) == n1); // Sanity check: head's value is 10
// size==2
int n2 = 11;
append(&n2, &head, &tail);
assert(head != tail); // Sanity check: head and tail are same (size==1)
assert(*(head -> a_value) == n1); // Sanity check: head's value is 10
assert(*(tail -> a_value) == n2); // Sanity check: tail's value is 11
assert(tail -> next == NULL);
print_list(head);
destroy_list(&head, &tail);
return EXIT_SUCCESS;
}
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