C LinkedList printing

Question

我正在编写一个程序，从txt文件中读取并将内容添加到链表中。然后，使用命令提示符中的用户界面，我应该能够查看列表，从列表中添加/删除，并使用部件号在列表中搜索项目以查看其完整细节。

目前我遇到两个问题:

1。在main函数的切换案例1中，我插入了一个节点tempNODE->项。dataitem = getInfo();line在while循环之外正常工作，但是当我将它放入while循环中时，它跳过接受新项目的名称，直接转到部件号。我不明白它为什么会这样。

2。在主函数的切换情况3中，我无法弄清楚如何打印搜索节点的内容，DisplayNode函数由于node结构内部的联合而无法工作(我想弄清楚如何在不改变node结构的情况下打印这个)。

这是我当前的代码:

#include "stdafx.h"
#include <stdio.h>
#include <stdlib.h>
#include <stddef.h>
typedef struct inventory
{
    char invName[36];
    int  invPartNo;
    int  invQOH;
    float invUnitCost;
    float invPrice;
}stock;
struct  NODE
{
    union
    {
        int  nodeCounter;
        void  *dataitem;
    }item;
    struct NODE *link;
};
struct NODE *InitList();
void DisplayNode(struct inventory *);
struct inventory * ReadData(FILE *);
void DisplayList(struct NODE *);
struct NODE* GetNode(FILE *);
void  Add2List(struct NODE *, struct NODE *);
struct NODE* SearchList(struct NODE *, int );
void  DeleteNode(struct NODE *, int );
void readFromText(FILE *, struct NODE *);
struct inventory *getInfo();
int main(int argc, char* argv[])
{
    //create new linked list
    struct NODE *header;
    header = InitList();
    //open text file and read all inputs into the linked list
    FILE *fp = fopen("input.txt", "r");
    readFromText(fp, header);
    //divider
    printf("n--------------------------------------------------nn");
    int input = 0;
    int a = 0;
    struct NODE *tempNODE = (struct NODE*)malloc(sizeof NODE);
    //tempNODE->item.dataitem = getInfo(); //lets user input info from cmd
    //Add2List(header, tempNODE); //inserts the new node into the list
    while(a == 0)
    {
        printf("nnEnter a number to select an option: n");
        printf("1 Insert item n");
        printf("2 Delete item n");
        printf("3 Look up item n");
        printf("4 Print current list of items n");
        printf("5 Exit n");
        scanf("%d", &input);
        switch(input)
        {
        case 1:
            //insert a node (Add2List function)
            tempNODE->item.dataitem = getInfo(); //lets user input info from cmd
            Add2List(header, tempNODE); //inserts the new node into the list
        break;
        case 2:
            printf("Enter item number to delete n");
            int iNumber;
            scanf("%d", &iNumber);
            DeleteNode(header, iNumber);
            printf("Item %d deleted", iNumber);
        break;
        case 3:
            printf("Enter item number to search n");
            int searchNumber;
            scanf("%d", &searchNumber);
            //create temp node to take value from search
            //struct NODE *tempNODE = (struct NODE*)malloc(sizeof NODE);
            tempNODE = SearchList(header, searchNumber); //returns a node
            //display node contents
            //DisplayNode(tempNODE->item);
        break;
        case 4:
            DisplayList(header);
        break;
        case 5:
            a = 1; //ends the while loop
        break;
        default:
            a = 1; //ends the while loop
        }
    }
    //divider
    printf("n--------------------------------------------------nn");
    return 0;
}
struct NODE *InitList()
{
    struct NODE *temp = (struct NODE*)malloc(sizeof NODE);
    temp->item.nodeCounter = 0;
    temp->link = NULL;
    return temp;
}

void  Add2List(struct NODE *start, struct NODE *NewNode)
{
    struct NODE *current = start;
    while (current->link != NULL)
        current = current->link;
    current->link = NewNode;
    NewNode->link = NULL;
    start->item.nodeCounter++;
}

struct NODE* GetNode(FILE *fptr)
{
    struct NODE *temp = (struct NODE*)malloc(sizeof NODE);
    temp->item.dataitem = ReadData(fptr);
    temp->link = NULL;
    return temp;
}

void DisplayList(struct NODE *start)
{
    struct NODE *current = start->link;
    while (current != NULL)
    {
        DisplayNode((struct inventory *)current->item.dataitem);
        current = current->link;
    }
}

void DisplayNode(struct inventory *stuff)
{
    printf("Name: %sn", stuff->invName);
    printf("Part Number: %.5dn", stuff->invPartNo);//printf(“ %.9d”, x)
    printf("Quantity on hand: %dn", stuff->invQOH);
    printf("Unit Cost: %0.2fn", stuff->invUnitCost);
    printf("Price %0.2fnn", stuff->invPrice);
}

struct inventory * ReadData(FILE *fptr)
{
    struct inventory *temp = (struct inventory *)malloc(sizeof inventory);
    if(fptr==stdin)
        printf("Enter item name: ");
    fscanf_s(fptr, "%s", temp->invName);
    if(fptr==stdin)
        printf("Enter item part number: ");
    fscanf_s(fptr, "%d", &temp->invPartNo);
    if(fptr==stdin)
        printf("Enter item quantity on hand: ");
    fscanf_s(fptr, "%d", &temp->invQOH);
    if(fptr==stdin)
        printf("Enter item unit cost: ");
    fscanf_s(fptr, "%f", &temp->invUnitCost);
    if(fptr==stdin)
        printf("Enter item price: ");
    fscanf_s(fptr, "%f", &temp->invPrice);
    return temp;
}
struct NODE* SearchList(struct NODE *start, int oldData)
{
    struct NODE* current = start;
    struct inventory * st = (struct inventory *)current->link->item.dataitem;
    while (st->invPartNo != oldData && current != NULL)
    {
        current = current->link;
        if(current->link)
            st = (struct inventory *)current->link->item.dataitem;
    }
    return current;
}
void  DeleteNode(struct NODE *start, int oldData)
{
    struct NODE *current, *oldNode;
    current = SearchList( start, oldData);
    oldNode = current->link;
    current->link = oldNode->link;
    free(oldNode);
    start->item.nodeCounter -= 1;
}
void readFromText(FILE *fp, struct NODE *header)
{
    if( fp != NULL )
    {
        while(!feof(fp))
        {
            struct NODE *nNode =  (struct NODE*)malloc(sizeof NODE);
            struct inventory *newNode =  (struct inventory*)malloc(sizeof inventory);
            fgets(newNode->invName, 100, fp);
            fscanf(fp, " %d %d %f %f ", &newNode->invPartNo,&newNode->invQOH,&newNode->invUnitCost,&newNode->invPrice);
            nNode->item.dataitem = newNode;
            header->item.nodeCounter++;
            Add2List(header, nNode);
        }
     }
}
struct inventory *getInfo()
{
    struct inventory *temp =  (struct inventory*)malloc(sizeof inventory);
    printf("Enter item name: ");
    scanf("%99[^n]", temp->invName); //scans whole line up to 99 characters or until n
    printf("Enter item part number: ");
    scanf("%d", &temp->invPartNo);
    printf("Enter item quantity on hand: ");
    scanf("%d", &temp->invQOH);
    printf("Enter item unit cost: ");
    scanf("%f", &temp->invUnitCost);
    printf("Enter item price: ");
    scanf("%f", &temp->invPrice);
    return temp;
}

这是我读取的文本文件:

#1 Flat Blade Screwdriver
12489
36
.65
1.75
#2 Flat Blade Screwdriver
12488
24
.70
1.85
#1 Phillips Screwdriver
12456
27
0.67
1.80
#2 Phillips Screwdriver
12455
17
0.81
2.00
Claw Hammer
03448
14
3.27
4.89
Tack Hammer
03442
9
3.55
5.27
Cross Cut Saw
07224
6
6.97
8.25
Rip Saw
07228
5
6.48
7.99
6" Adjustable Wrench
06526
11
3.21
4.50

Answer 1

1。在main函数的切换案例1中，我插入了一个节点tempNODE->项。dataitem = getInfo();线路外工作正常while循环，但是当我把它放入while循环时，它会跳过取新项目的名称并直接转到部件号。我不明白它为什么会这样。

这是因为你在第241行传递给scanf()的格式字符串没有指定读取任何内容。也就是说，你有这个:

scanf("%99[^n]", temp->invName); //scans whole line up to 99 characters or until n

scanf("%99s[^n]", temp->invName); //scans whole line up to 99 characters or until n

2。在main函数的切换案例3中，我不知道如何打印搜索节点的内容，即DisplayNode函数将不起作用，因为NODE(1)的结构内部有联合我想弄清楚如何打印这个不改变的结构节点)。

那么，你可以像这样打印联合:

printf("tempNODE->item.nodeCounter=%in", tempNODE->item.nodeCounter);
printf("tempNODE->item.dataitem=%pn", tempNODE->item.dataitem);

当然要注意这两个打印线将显示不正确/不相关的信息对任何特定节点,因为联盟只能一次其组成成员之一——例如,如果特定节点将举行nodeCounter(整数)值,那么您就不需要访问dataitem成员值在第二行,或者如果节点将数据项(指针)值,那么你不应该访问nodeCounter成员变量。所以你应该有办法知道这两个联合成员中哪个是有效的，哪个不是。典型的方法是向结构体(在联合之外)添加一个单独的成员，您设置该成员来指示联合被设置为什么——这被称为标记联合。但如果你不这样做，你就必须想出其他的机制来代替。