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 72 73 | #include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <assert.h>
#include "log_macros.h"
typedef struct _Node { // always called Node or ▒Node in ECE 26400
int value; // usually called 'value' // 4 bytes¹ for int
struct _Node* next; // address of the next node in the list // 8 bytes¹ for ▒▒▒▒▒*
} Node; // Think of .next as your link to the next node.
// ¹ Disclaimer: On our platform; sizes on other platforms may vary.
void append(int value, Node** a_head, Node** a_tail) {
Node* new_tail = malloc(sizeof(*new_tail));
if(*a_head == NULL) { // If list is empty
*a_head = new_tail; // store the address of the new tail at address a_head.
}
else {
(*a_tail) -> next = new_tail; // append to end of list
}
*a_tail = new_tail;
// NO MATTER WHAT…
assert((*a_tail) -> value == value);
assert((*a_tail) -> next == NULL);
assert((*a_head) != NULL); // Because if we added anything, list is not empty.
}
void print_list(Node* head) {
for(Node* curr = head; curr != NULL; curr = curr -> next) {
log_int(curr -> value);
}
}
// YOU CANNOT ACCESS MEMORY AFTER IT HAS BEEN FREED.
void destroy_list(Node** a_head, Node** a_tail) {
while(*a_head != NULL) {
// Save the new head
Node* new_head = (*a_head) -> next;
// Free the old head
free(*a_head);
// Set 'head' to the address of new head
*a_head = new_head;
}
assert(*a_head == NULL);
*a_tail = NULL;
// NOTE: *a_head and *a_tail will be NULL at the end so we can't accidentally access.
}
int main(int argc, char* argv[]) {
// size==0 - empty list
Node* head = NULL; // first node in the list is always called 'head'
Node* tail = NULL; // last node in the list is always called 'tail'
append(10, &head, &tail);
append(11, &head, &tail);
append(12, &head, &tail);
print_list(head);
// [ 10 | → ] → [ 11 | → ] → NULL
destroy_list(&head, &tail);
return EXIT_SUCCESS;
}
/* vim: set tabstop=4 shiftwidth=4 fileencoding=utf-8 noexpandtab: */
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