1 #include <stdio.h> 2 #include <stdlib.h> 3 4 typedef struct node { 5 char c; 6 struct node *next; 7 } node_t, *node_p; 8 9 void insert(node_p *list, char c); 10 void destroy(node_p *list); 11 12 void print_list(node_p *first); 13 14 int main (void) 15 { 16 node_p node = NULL; 17 /* Now node points to NULL */ 18 19 insert(&node, 'A'); 20 /* Now node points to a struct containing the char 'A' */ 21 22 insert(&node, 'B'); 23 print_list(&node); 24 25 destroy(&node); 26 27 return 0; 28 } 29 30 void insert(node_p *list, char c) 31 { 32 /* Create new node */ 33 node_p new_node; 34 new_node = malloc(sizeof(node_t)); 35 36 /* Storing the value on the new node */ 37 new_node->c = c; 38 39 /* Storing the next node in a pointer on the new node */ 40 new_node->next = *list; 41 42 /* Now node points to the new node */ 43 *list = new_node; 44 } 45 46 void print_list(node_p *list) 47 { 48 if(*list == NULL) 49 printf("List is empty.\n"); 50 51 /* New node pointer to iterate over the list */ 52 node_p current_node; 53 current_node = *list; 54 55 while(current_node != NULL) { 56 printf("%c --> ", current_node->c); 57 if(current_node->next == NULL) 58 printf("NULL\n"); 59 60 current_node = current_node->next; 61 } 62 } 63 64 void destroy(node_p *list) 65 { 66 /* Frees memmory from first to last */ 67 if(*list == NULL) 68 return; 69 70 /* current it's a pointer to iterate over the list */ 71 /* tmp stores a copy of current to avoid losing the memory location */ 72 node_p current, tmp; 73 current = *list; 74 75 while(current != NULL) { 76 tmp = current; 77 78 current = current->next; 79 80 printf("freeing %c\n", tmp->c); 81 free(tmp); 82 } 83 printf("All nodes were freed correctly.\n"); 84 }
