Question

我最近在编程功课方面遇到了很多麻烦。我不知道怎么去交换功能。我甚至不确定我是否正确编写了其他两个函数。我需要一些关于如何做到这一点的指导，因为每当我尝试在交换函数中做任何事情时，我都会得到“请求成员不是结构或联合。

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "StudentRecord.h"
#include "StudentRecordNode.h"

void parseFile(char* filename, struct student_record_node** head);

int main(int argc, char* argv[])
{

struct student_record_node* head = student_record_allocate();


parseFile(argv[1], &head);
printf("Before sorting...\n");
printNodeList(head);
printf("Sorting by age...\n");
sort(&head, *ageComparator);
printNodeList(head);

}

void parseFile(char* filename, struct student_record_node** head)
{
int i = 0;
struct student_record_node* newNode = *head;
FILE* fp;
fp = fopen(filename, "r");
if (fp == NULL)
{
    printf("Input file could not be read\n");
    exit(1);
}

while(1)
{
    if(newNode != *head)
    {
        newNode = student_record_allocate();
        appendNode(*head, newNode);
    }

    fscanf(fp, "%s %s %d %d", newNode->record_->first_name_, newNode->record_->last_name_, 
&newNode->record_->student_id_, &newNode->record_->student_age_);

    if(newNode == *head)
    {
        newNode = NULL;
    }
    if(feof(fp))
    {
        break;
    }
}
fclose(fp);
}

我的main.c

然后是我的StudentRecordNode.h

#ifndef STUDENTRECORDNODE_H
#define STUDENTRECORDNODE_H
#include "StudentRecord.h"

struct student_record_node
{
    struct student_record* record_;
    struct student_record_node* next_;
    struct student_record_node* prev_;
};

struct student_record_node* student_record_allocate()
{
    struct student_record_node* newNode;
    newNode = calloc(1, sizeof(struct student_record_node));
    if (newNode == NULL)
    {
        printf("No memory allocated for newNode");
            exit(1);
    }

    newNode->record_ = calloc(1, sizeof(struct student_record));
    if (newNode->record_ == NULL)
    {
        printf("No memory allocated for record_");
        exit(1);
    }
    newNode->next_ = NULL;
    return newNode;
}

void appendNode(struct student_record_node* head, struct student_record_node* newNode)
{
    int i = 1;
    struct student_record_node* current = head;

    while(i)
    {
        if (current->next_ == NULL)
        {
            current->next_ = newNode;
            i = 0;
        }
        current = current->next_;
    }
}

void printNode(struct student_record_node* node)
{
    printf("struct student_record_node:\n");
    printf("\tStudent first name: %s\n", node->record_->first_name_);
    printf("\tStudent last name: %s\n", node->record_->last_name_);
    printf("Student id: %d\n", node->record_->student_id_);
    printf("Student age: %d\n", node->record_->student_age_);
}

void printNodeList(struct student_record_node* head)
{
    struct student_record_node* current = head;
    while(current->next_ != NULL)
    {
        printNode(current);
        current = current->next_;
    }
    printf("\n");
}

void swap(struct student_record_node** node1, struct student_record_node** node2)
{
    struct student_record_node* ptr;
    struct student_record_node* ptr2;

    ptr = *node1;
    ptr2 = *node2;
    if (ptr == ptr2)
    return;

    ptr->next_ = ptr2->next_;
    ptr2->prev_ = ptr->prev_;

    if (ptr->next_ != NULL)
        ptr->next_->prev_ = ptr;

    if (ptr2->prev_ != NULL)
        ptr2->prev_->next_ = ptr2;

    ptr2->next_ = ptr;
    ptr->prev_ = ptr2;

}


void sort(struct student_record_node** recordsHead, int (*compare_fcn)(struct student_record_node*, struct student_record_node*))
{
    int swapped, i;
    struct student_record_node* ptr;
    struct student_record_node* ptr2 = NULL;

    if (*recordsHead == NULL)
        return;

do
{

    swapped = 0;
    ptr = *recordsHead;

    while(ptr->next_ != ptr2)
    {
        if(compare_fcn(ptr, ptr->next_) > 0)
        {
            swap(&ptr, &ptr->next_);
            if(ptr == *recordsHead)
            {
            (*recordsHead) = ptr->prev_;
            }
        swapped = 1;
        }

    else
    {
        ptr = ptr->next_;
    }
    }
    ptr2 = ptr;
}
while(swapped);
}

int ageComparator(struct student_record_node* node1, struct student_record_node* node2)
{
    int a = 1;
    struct student_record_node* ptr;
    struct student_record_node* ptr2;

    ptr = node1;
    ptr2 = node2;   

    if (ptr->record_->student_age_ > ptr2->record_->student_age_&&ptr->next_ != NULL)
    return a; 

    else
    return 0;

}

int idComparator(struct student_record_node* node1, struct student_record_node* node2)
{
    int a = 1;

    if (node1->record_->student_id_ > node2->record_->student_id_)
    {
        return a;
    }

    else
    {
        return 0;
    }
}

void student_record_node_deallocate(struct student_record_node* node)
{
    struct student_record_node* temp;
    temp = node;
    free(temp->record_);
    free(temp);
}

void freeNodeList(struct student_record_node* head)
{
    while(head != NULL)
    {
        student_record_node_deallocate(head);
        head = head->next_;
    }
}

#endif

请告诉我这些功能是否有问题。我认为唯一有问题的是swap，sort和ageComparator函数（忽略idComparator）。谢谢。

编辑：我很蠢。我想出了我一直得到的错误。我的程序现在差不多了。问题是，当我按年龄和id排序时，我重新输入它们，它将打印它们排序。但是，由于第一个节点现在完全为NULL，它似乎已将所有元素向上推升一个位置。所有信息都是0或NULL，但显然所有填充信息的元素都在列表中。

https://puu.sh/vvlVr/96605bcc35.png

这就是我的意思。任何帮助表示赞赏。拜托，谢谢你。

C编程：节点的链接LIst交换位置

0 个答案: