c - 用 C 中的结构对链表进行排序

Question

我尝试使用我在一个程序中学到的冒泡排序方法，该程序用于对已插入链表的书籍进行排序。我试过交换 2 个节点，但这导致 nextptr 也被交换。我启动了这个名为 authsort 的新功能，它没有引用书籍结构中的成员。我需要改变什么才能使这种工作正常进行？

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

struct book
{
    char author[30];
    char title[50];
    char hold2[50];
    char titleins[50];
    char genre[15];
    int rating;
    int comma;
    int titleshift;
    int number;
};
struct listnode
{
    struct book data;
    struct listnode *nextptr;
};
    typedef struct listnode LISTNODE;
    typedef LISTNODE *LISTNODEPTR;



    void insert(LISTNODEPTR *sptr, struct listnode data);
    void authsort(LISTNODEPTR sptr, struct listnode data);
    void freenodes(LISTNODEPTR currentptr);
    int add_2 (count, i, j, index, tag);
    void print_list(LISTNODEPTR, struct listnode book);
    int main ()
    {
        LISTNODEPTR startptr = NULL;
        struct listnode listnode;
        struct book book;
        int choice = 0;
        char item;
        int count = 0;
        int index = 0;
        int j = 0;
        char * pch2;
        char string[40];
        char string2[40];
        char * pch;
        int i = 0;
        while( choice != 2)
        {
        printf("What Would You Like To Do?\n");
        printf("1.Add Books\n2.exit\n3:sort by author\n");
        scanf("%d", &choice);
        getchar();




    switch(choice)
    {
        case 1:
                printf("Enter your book title:");
                gets(listnode.data.title);
                for(i=0;i<100;i++)
                {
                    listnode.data.title[i] = tolower(listnode.data.title[i]);
                }
                printf("Enter the author:");
                if(listnode.data.title[0] == 't')
                    {
                        if(listnode.data.title[1] == 'h')
                        {
                            if(listnode.data.title[2] == 'e')
                            {
                                if(listnode.data.title[3] == ' ')
                                {
                                    book.titleshift = 4;
                                    pch = strtok(listnode.data.title, " ");
                                    strcpy(string, pch);
                                    pch2 = strtok(NULL, "");
                                    book.comma = strlen(pch2);
                                    strcpy(string2, pch2);
                                    strncat(string2, string, 20);
                                    strncpy(listnode.data.title, string2, 50);

                                }
                            }
                        }
                    }
                if(listnode.data.title[0] == 'a')
                {
                    if(listnode.data.title[1] == ' ')
                    {
                        book.titleshift = 2;
                        pch = strtok(listnode.data.title, " ");
                        strcpy(string, pch);
                        pch2 = strtok(NULL, "");
                        book.comma = strlen(pch2);
                        strcpy(string2, pch2);
                        strncat(string2, string, 20);
                        strncpy(listnode.data.title, string2, 50);
                    }
                }
                gets(listnode.data.author);
                for(i=0;i<100;i++)
                {
                    listnode.data.author[i] = tolower(listnode.data.author[i]);
                }
                printf("Enter the genre:");
                gets(listnode.data.genre);

                for(i=0;i<100;i++)
                {
                    listnode.data.genre[i] = tolower(listnode.data.genre[i]);
                }
                printf("Enter the quality:");
                scanf("%d", &listnode.data.rating);
                printf("Enter the number of pages:");
                scanf("%d", &listnode.data.number); // after scanning in from user, we insert and print the list
                insert(&startptr, listnode);
                print_list(startptr, listnode);
                break;
        case 2:
        freenodes(startptr);
        break;
        case 3:
        authsort(startptr, listnode);
        print_list(startptr, listnode);
        break;
    }
        }
    return 0;
}


/*********************************FUNCTION*********************************/
void print_list(LISTNODEPTR currentptr, struct listnode book)
{

    if (!currentptr)
        printf("List is empty.\n\n");
    else
     {
        printf("your list:\n");
         while (currentptr)

         {
             if(currentptr->data.comma > 1)
                {

             printf("%-15s %-20s %-15s %-15d %-15d\n", currentptr->data.author, currentptr->data.title, currentptr->data.genre, currentptr->data.rating, currentptr->data.number);
            currentptr = currentptr -> nextptr; // this will continue printing as long as there in a nextptr, or book

                }

                else if(currentptr->data.comma == 0)
                {
                    printf("%-15s %-20s %-15s %-15d %-15d\n", currentptr->data.author, currentptr->data.title, currentptr->data.genre, currentptr->data.rating, currentptr->data.number);
                    currentptr = currentptr -> nextptr; // this will continue printing as long as there in a nextptr, or book

                }
         }

        if(!currentptr)
        {
            printf("end of list\n\n");

        }
     }
}

/*********************FUNCTION******************/
void insert(LISTNODEPTR *sptr, struct listnode data)
{
     LISTNODEPTR newptr, previousptr, currentptr;
     newptr = malloc(sizeof(LISTNODE));
     int i = 0;

        if (newptr)
        {



            strcpy(newptr -> data.title,data.data.title);

            //if(book.titleshift == 0)
            //{

            //strcpy(newptr -> title,book.title);
            //}
            // here the books are being copied into the current node
            strcpy(newptr -> data.author, data.data.author);
            strcpy(newptr -> data.genre, data.data.genre);
            newptr -> data.rating= data.data.rating;
            newptr -> data.number= data.data.number;
            newptr -> nextptr = NULL;
            previousptr = NULL;
            currentptr = *sptr;

     while (currentptr != NULL && strcmp(data.data.title, currentptr -> data.title)>0)
                            // this compares the titles to insert by author
     {
        previousptr = currentptr;
        currentptr = currentptr -> nextptr;
     }
        if (previousptr == NULL)
        {
        newptr -> nextptr = *sptr;
        *sptr = newptr;
        }
        else
        {
            previousptr -> nextptr = newptr;
            newptr -> nextptr = currentptr;
        }
            }
            else
            {
                printf("Not inserted.\n");
            }
}

/*******************************FUNCTION***********************************/

/**************************FUNCTION*********************/
void freenodes(LISTNODEPTR currentptr)
{
 LISTNODEPTR tempptr;
 while(currentptr!=NULL)
 {
  tempptr=currentptr->nextptr;
  free(currentptr);
  currentptr=tempptr;
 }
}

void authsort(LISTNODEPTR sptr, struct listnode data)
{
    LISTNODEPTR nextptr;
    LISTNODEPTR previousptr;
    LISTNODEPTR currentptr;
    LISTNODEPTR tempptr;
    LISTNODEPTR trail;
        int count = 0;
        int j = 0;
        while(sptr != NULL)
        {
            count++;
            sptr = sptr -> nextptr;
        }
        for(j=0;j<count;j++)
        {

        currentptr = sptr;
        while(currentptr->nextptr != NULL)
        {


            if(strcmp(currentptr ->data.author, currentptr->nextptr.data.author)>0)
            {
                tempptr = currentptr ->nextptr;
                currentptr ->nextptr = currentptr ->nextptr->nextptr;
                currentptr ->nextptr = currentptr;


                if(currentptr == sptr)
                  sptr = trail = tempptr;
                else
                  trail->nextptr = tempptr;
                currentptr = tempptr;
              }

              trail = currentptr;
              currentptr = currentptr->nextptr;
        }

        }



}

Answer 1

看，您的最终目标应该是拥有一个已排序的链表。现在您正在尝试对两个节点进行排序，但您甚至可以交换它们的数据!

这不涉及指针重定位，并且使您的程序更易于分析和理解。我希望这能提示您找到正确的解决方案!

快乐编码:)