循環鏈表實例程序（C語言）

使用 C語言來實現循環鏈表的實例程序，如下所示：

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <stdbool.h>

struct node {
int data;
int key;
struct node *next;
};

struct node *head = NULL;
struct node *current = NULL;

bool isEmpty(){
return head == NULL;
}

int length(){
int length = 0;

//if list is empty
if(head == NULL){
return 0;
}

current = head->next;

while(current != head){
length++;
current = current->next;
}
return length;
}

//insert link at the first location
void insertFirst(int key, int data){
//create a link
struct node *link = (struct node*) malloc(sizeof(struct node));
link->key = key;
link->data = data;

if (isEmpty()) {
head = link;
head->next = head;
}
else{
//point it to old first node
link->next = head;
//point first to new first node
head = link;
}
}

//delete first item
struct node * deleteFirst(){
//save reference to first link
struct node *tempLink = head;

if(head->next == head){
head = NULL;
return tempLink;
}

//mark next to first link as first
head = head->next;

//return the deleted link
return tempLink;
}

//display the list
void printList(){
struct node *ptr = head;
printf("\n[ ");

//start from the beginning
if(head != NULL){
while(ptr->next != ptr){
printf("(%d,%d) ",ptr->key,ptr->data);
ptr = ptr->next;
}
}
printf(" ]");
}

main() {

insertFirst(1,10);
insertFirst(2,20);
insertFirst(3,30);
insertFirst(4,1);
insertFirst(5,40);
insertFirst(6,56);

printf("Original List: ");
//print list
printList();

while(!isEmpty()){
struct node *temp = deleteFirst();
printf("\nDeleted value:");
printf("(%d,%d) ",temp->key,temp->data);
}

printf("\nList after deleting all items: ");
printList();
}

如果我們編譯並運行上述程序那麼這將產生以下結果 -

Original List:
[ (6,56) (5,40) (4,1) (3,30) (2,20) ]
Deleted value:(6,56)
Deleted value:(5,40)
Deleted value:(4,1)
Deleted value:(3,30)
Deleted value:(2,20)
Deleted value:(1,10)
List after deleting all items:
[ ]