c - 问题在链表中的特定位置插入节点

Question

我对函数 insertnodespecific 有一些问题。当我运行这个程序时，我首先使用 insertNodeFirst() 函数，然后使用 insertNodeEnd() 函数。然后我运行 list listNode() 函数，一切都很好。但是，当我尝试使用 insertNodeSpecific 函数时，该节点要么被添加为链表中的最后一个，要么被添加到另一个位置。任何人都可以看到该功能有问题吗？我假设该函数看起来类似于 insertNodeEnd() 函数。

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


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

struct node *head = NULL;
void insertNodeFirst();
void insertNodeEnd();
void insertNodeSpecific();
void listNode();

int choice = 0;


int main()
{

    while(true)
    {
    printf("Enter a choice:\n"
    "1: Insert a node at the beginning of the list:\n"
    "2: Insert a node at the end of the list:\n"
    "3: Insert a node at a specific position in the list:\n"
    "4: List nodes: \n"
    "5: Exit: \n");

    scanf("%d", &choice);

        switch (choice){
            case 1:
                insertNodeFirst();
                break;

            case 2:
                insertNodeEnd();
                break;

            case 3:
                insertNodeSpecific();
                break;

            case 4:
                listNode();
                break;

            case 5:
                exit(0);
                return 0;

            default:
               printf("Invalid choice! \n");
               break;
    }
}
    return 0;
}




void insertNodeFirst()
{
    int data;
    int key;
    printf("Type in a value: \n");
    scanf("%d", &data);
    struct node *link = (struct node*)malloc(sizeof(struct node));
    link->key = key;
    link->data = data;

    link->next = head;      // point to old first node
    head = link;            // point to new first node


}




void insertNodeEnd()
{
    int data;

    printf("Type in a value: \n");
    scanf("%d", &data);

    struct node *newNode, *temp;
    newNode = (struct node*)malloc(sizeof(struct node));

    if(newNode == NULL)
    {
        printf("Unable to allocate memory! \n");
    }
    else
    {
        newNode->data = data;
        newNode->next = NULL;
        temp = head;
    }

    while(temp != NULL && temp->next != NULL)
    {
        temp = temp->next;
    }

    temp->next = newNode; //inserted data

}



void insertNodeSpecific()
{
    int data = 0;
    int pos = 0;
    int i;

    printf("Type in a value:  \n");
    scanf("%d", &data);

    printf("Enter a position: \n");
    scanf("%d", &pos);

    struct node *temp2, *insertnode;
    insertnode = (struct node*)malloc(sizeof(struct node));

    insertnode->next = NULL;
    temp2 = head;

    insertnode->data = data;


    if(temp2 == NULL)
    {
        printf("Unable to allocate memory! \n");
    }

    while(pos--)
    {
        temp2 = temp2->next;
    }

    temp2->next = insertnode;

}


void listNode()
{
    struct node *ptr = head;
    printf("List of nodes are:\n");
    while(ptr != NULL)
    {
        printf("\n%d\n", ptr->data);
        ptr = ptr->next;
    }

    printf("\n");

}

标签： clistinsertpositionnodes