C語言逆向列印雙向連結串列程式

建立一個雙向連結串列，並逆向列印此雙向連結串列中的資料項的範例程式，將以下程式碼儲存到一個原始檔中：display_doubly_linked_list_in_reverse.c， 如下所示 -

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

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

struct node *head = NULL;
struct node *last = NULL;

struct node *current = NULL;

//display the list
void printList() {
    struct node *ptr = head;

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

    printf(" [last]\n");
}

//display the list
void print_backward() {
    struct node *ptr = last;

    printf("\n[head] <=>");
    //start from the beginning
    while (ptr != NULL) {
        printf(" %d <=>", ptr->data);
        ptr = ptr->prev;
    }

    printf(" [last]\n");
}

//Create Linked List
void insert(int data) {
    // Allocate memory for new node;
    struct node *link = (struct node*) malloc(sizeof(struct node));

    link->data = data;
    link->prev = NULL;
    link->next = NULL;

    // If head is empty, create new list
    if (head == NULL) {
        head = link;
        return;
    }

    current = head;

    // move to the end of the list
    while (current->next != NULL)
        current = current->next;

    // Insert link at the end of the list
    current->next = link;
    last = link;
    link->prev = current;
}

int main() {
    insert(10);
    insert(20);
    insert(30);
    insert(40);
    insert(50);
    insert(60);

    printList();
    print_backward();

    return 0;
}

執行上面程式，得到以下結果 -

[head] <=> 10 <=> 20 <=> 30 <=> 40 <=> 50 <=> 60 <=> [last]

[head] <=> 60 <=> 50 <=> 40 <=> 30 <=> 20 <=> 10 <=> [last]