Question

我想在headnode或其他节点后面添加newnode但是节点没有添加whay我应该这样做吗？

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

typedef struct node {
int val;
struct node *next;

} Node;

Node *head, *tail, *behind, *prev,*twonext;

Node *new_node(int val){
struct node *ptr = malloc(sizeof(*ptr));
if(ptr==NULL){
    perror("malloc:");
    printf("\nFailed to create a new node.\n");
    return NULL;
}
ptr->val  = val;
ptr->next = NULL;

return ptr;
}

Node *creatFirstNode(int val){
return head = tail = new_node(val);
}

void printList(void){
Node *np = head;

printf("\n----Value in Liked list----\n");
while(np){
    printf("[%d], ", np->val);
    np = np->next;
}
 // printf("NULL\n");
}

void freeList(void){
while(head){
    Node *np = head->next;
    free(head);
    head = np;
}
tail = NULL;
}

int main(void){
char cmd =' ';
int k;

printf("\n-------- Welcome to Linked List Program -----------\n\n");

do {
    int v = 0;
    int s = 0;

    printf("\nAdd to 'h'ead or 't'ail or 'b'ehind value or 'p'rint or 'q'uit:");   
    scanf(" %c", &cmd);
    fflush(stdin);
    switch(cmd){

添加headnode --------------------------------------------- -----------------------

    case 'h':
        printf("Enter value node head:");
        scanf("%d", &v);
        if(head == NULL){
            creatFirstNode(v);
        } else {
            Node *np = new_node(v);
            np->next = head;
            head = np;
        }
        fflush(stdin);
        printList();
        break;

添加尾节点-------------------------------------------- ------------------------

    case 't':
        printf("Enter value node tail:");
        scanf("%d", &v);
        if(head == NULL){
            creatFirstNode(v);
        } else {
            tail = tail->next = new_node(v);

        }
        fflush(stdin);
        printList();
        break;

添加节点我在这里有问题我该怎么办？ -----------------------------------------------

    case 'b':
            printf("Enter node value:");
            scanf("%d",&v);
            Node *np = new_node(v);
            printf("Adding value [%d] in new node:",v);

        //  behind = behind->next = new_node(v);
        if(head == NULL)
        {
        printf("No node to insert behind:");

        }
        else
        {

            printf("\nAdd new node behind the value:");
            scanf("%d", &s);

            np = head;
            while(np->val != s);

            {
                prev=np;
                np =np->next;

            }

            twonext=np->next;

            np->next=NULL;
            np->next=twonext;

        }
        fflush(stdin);
        printList();
        break;

    /*case 'p':
        printList();
        break;
        */
    case 'q':
        freeList();
        printf("\nBye!\n");
        getch();
        break;

    default:
        printf("\n     Invalid Input     ");
    }
}while(cmd != 'q' );

return 0;
}

Answer 1

基本上，如果您想在其他节点之间放置一个新节点，您需要将prev-＆gt; next与新节点相关联，将new-＆gt; next与下一个节点相关联。这就是全部，这是一个代码示例。

case 'b':
            printf("Enter node value:");
            scanf("%d",&v);
            Node *np = new_node(v);
            printf("Adding value [%d] in new node:",v);

        //  behind = behind->next = new_node(v);
        if(head == NULL)
        {
            printf("No node to insert behind:");

        }
        else
        {

            printf("\nAdd new node behind the value:");
            scanf("%d", &s);

            Node *tmp = head; /*You need a tmp variable to go through the list*/
            while(tmp->val != s && tmp != NULL);

            {
                prev=tmp; /*Save the prev node*/
                tmp =tmp->next; /*Go through*/

            }
            if(tmp != NULL){
                prev->next = np; /*Link the prev with the new*/
                np->next = tmp; /*Link the new one with the subsequent*/
            }
        }
        fflush(stdin);
        printList();
        break;

C链表节点不添加

1 个答案: