我在 C 代码中的错误是什么？这是一个需要使用 FILE 处理和 BST 的图书馆目录

Question

1) 我坚持插入和显示用户输入。我很困惑何时使用 fwrite，无论是在 addRecord 函数内还是在 insert 函数内。

2)输入后写还是插入后写?

无论如何，我的代码是这样的：

#include<stdio.h> #include<conio.h> #include<stdlib.h> #include<string.h> #include<Windows.h> struct book{ char title[30]; char author[20]; char isbn[14]; char genre[10]; char publisher[30]; int year; char synopsis[150]; struct book *left; struct book *right; }; typedef struct book catalog; catalog *root; FILE *fx,*fy; int structsize=sizeof(catalog); void addBooks(); void removeBooks(); void modify(); void searchBook(); void perTitle(); void perAuthor(); void perISBN(); void perGenre(); void displayCatalog(catalog *root); int ifexists(char *x); void insert(catalog *root,catalog *x); catalog remove(catalog *root,catalog *x); void menu(); void gotoxy(int x,int y); void main(){ root=NULL; fx=fopen("CAT.dat","rb+"); if(fx==NULL){ fx=fopen("CAT.dat","wb+"); if(fx==NULL){ gotoxy(22,10); printf("No records to show..."); getch(); menu(); } } menu(); } void menu(){ int choice; system("cls"); gotoxy(22,5); printf("----------WELCOME TO THE CARD CATALOG----------"); gotoxy(22,7); printf("1] Add a book"); gotoxy(22,8); printf("2] Remove a book"); gotoxy(22,9); printf("3] Modify a book"); gotoxy(22,10); printf("4] Search a book"); gotoxy(22,11); printf("5] Display the catalog"); gotoxy(22,12); printf("6] Exit"); gotoxy(22,14); printf("Enter your choice: "); scanf("%d",&choice); switch(choice){ case 1: addBooks(); break; case 2: removeBooks(); break; case 3: modify(); break; case 4: searchBook(); break; case 5: displayCatalog(root); break; case 6: exit(0); } } void addBooks(){ char n; catalog *ptr; ptr=(catalog*)malloc(sizeof(catalog)); fx=fopen("CAT.dat","ab+"); fseek(fx,0,SEEK_END); system("cls");fflush(stdin); gotoxy(22,8); printf("Title: "); scanf("%[^\n]s",ptr->title);fflush(stdin); gotoxy(22,9); printf("Author: "); scanf("%[^\n]s",ptr->author);fflush(stdin); gotoxy(22,10); printf("Genre: "); scanf("%[^\n]s",ptr->genre);fflush(stdin); gotoxy(22,11); printf("ISBN: "); scanf("%[^\n]s",ptr->isbn);fflush(stdin); gotoxy(22,12); printf("Publisher: "); scanf("%[^\n]s",ptr->publisher);fflush(stdin); gotoxy(22,13); printf("Year: "); scanf("%d",&ptr->year);fflush(stdin); gotoxy(22,14); printf("Synopsis: "); scanf("%[^\n]s",ptr->synopsis);fflush(stdin); ptr->left=NULL; ptr->right=NULL; if(root==NULL){ root=ptr; } else { insert(root,ptr); } gotoxy(22,18); printf("Add another (y/n)? "); scanf("%c",&n); if(n=='y' || n=='Y'){ addBooks(); } fclose(fx); getch(); menu(); } void insert(catalog *root,catalog *x){ fx=fopen("CAT.dat","ab+"); fseek(fx,0,SEEK_END); if((x->isbn) < (root->isbn)){ if(root->left==NULL){ root->left=x; } else { insert(root->left,x); } } if((x->isbn) > (root->isbn)){ if(root->right==NULL){ root->right=x; } else { insert(root->right,x); } } fwrite(&x,structsize,1,fx); fclose(fx); getch(); } void removeBooks(){ catalog *ptr,*temp; int x; char title[20],y; system("cls"); if(root==NULL){ gotoxy(22,10); printf("No records to show..."); getch(); menu(); } gotoxy(22,10); printf("Enter title of book to delete: "); scanf("%s",title); ptr=root; while(ptr!=NULL){ if(strcmp(ptr->title,title)==0){ gotoxy(22,11); printf("The book is in the catalog."); gotoxy(22,12); printf("Title: %s",root->title); gotoxy(22,13); printf("Author: %s",root->author); } else { gotoxy(22,11); printf("No book with that title in the catalog."); getch(); menu(); } if(strcmp(ptr->title,title)==0){ gotoxy(22,14); printf("Remove book record? (y/n) "); if(getch()=='y'){ remove(root,ptr); menu(); } else { menu(); } } } } catalog remove(catalog *root,catalog *x){ catalog *temp; char y; if(x==root){ temp=root; free(temp); root=NULL; } else if(x->isbn < root->isbn){ *root->left=remove(root->left,x); } else if(x->isbn > root->isbn){ *root->right=remove(root->right,x); } else if(root==NULL){ gotoxy(22,10); printf("Nothing to remove..."); getch(); menu(); } printf("The book has been removed."); printf("Remove another book? (y/n) "); scanf("%c",&y); return *x; } void modify(){ catalog *ptr; int num; char title[20]; system("cls"); if(root==NULL){ gotoxy(22,10); printf("No records exist..."); getch(); menu(); } printf("Enter title of book to be modified: "); scanf("%s",title); ptr=root; while(ptr!=NULL){ if(strcmp(ptr->title,title)==0){ printf("Input new information."); printf("Title: "); scanf("%s",root->title); printf("Author: "); scanf("%s",root->author); printf("ISBN: "); scanf("%d",root->isbn); printf("Publisher: "); scanf("%s",root->publisher); printf("Year: "); scanf("%d",root->year); printf("Synopsis: "); scanf("%s",root->synopsis); printf("The book's information has been modified."); } else { printf("No book found."); break; } } getch(); menu(); } void searchBook(){ int choice; char title[20], author[20]; int num; system("cls"); if(root==NULL){ printf("No records to show..."); getch(); menu(); } gotoxy(22,10); printf("-----SEARCH A BOOK-----"); gotoxy(22,12); printf("1] By title"); gotoxy(22,13); printf("2] By author"); gotoxy(22,14); printf("3] By ISBN"); gotoxy(22,15); printf("4] Back to menu"); gotoxy(22,18); printf("Enter your choice: "); scanf("%d",&choice); switch(choice){ case 1: perTitle(); break; case 2: perAuthor(); break; case 3: perISBN(); break; case 4: perGenre(); break; case 5: menu(); } } void perTitle(){ catalog *ptr; char title[20], temp[20], ans; system("cls"); gotoxy(22,15); printf("Enter book title: "); scanf("%s",title);fflush(stdin); ptr=root; while(ptr!=NULL){ while(strcpy(temp,ptr->title)){ if(strcmp(temp,title)==0){ system("cls"); gotoxy(22,10); printf("That book is in the catalog."); gotoxy(22,11); printf("Title: %s",ptr->title); gotoxy(22,12); printf("Author: %s",ptr->author); gotoxy(22,13); printf("ISBN: %d",ptr->isbn); gotoxy(22,14); printf("Genre: %s",ptr->genre); gotoxy(22,15); printf("Publisher: %s",ptr->publisher); gotoxy(22,16); printf("Year: %d",ptr->year); gotoxy(22,17); printf("Synopsis: %s",ptr->synopsis);fflush(stdout); break; } else { gotoxy(22,10); printf("No records to show..."); } } printf("Try another? (y/n) "); scanf("%c",&ans);fflush(stdin); switch(ans){ case 'y': searchBook(); break; case 'n': menu(); } } } void perAuthor(){ catalog *ptr; char author[20],au[20],ans; system("cls"); gotoxy(22,15); printf("Enter author's name: "); scanf("%s",author);fflush(stdin); ptr=root; while(ptr!=NULL){ while(strcpy(au,ptr->title)){ if(strcmp(au,author)==0){ system("cls"); gotoxy(22,10); printf("That book is in the catalog."); gotoxy(22,11); printf("Title: %s",ptr->title); gotoxy(22,12); printf("Author: %s",ptr->author); gotoxy(22,13); printf("ISBN: %d",ptr->isbn); gotoxy(22,14); printf("Genre: %s",ptr->genre); gotoxy(22,15); printf("Publisher: %s",ptr->publisher); gotoxy(22,16); printf("Year: %d",ptr->year); gotoxy(22,17); printf("Synopsis: %s",ptr->synopsis); } else { gotoxy(22,10); printf("No records to show..."); } printf("Try another? (y/n) "); scanf("%c",&ans); switch(ans){ case 'y': searchBook(); break; case 'n': menu(); } } } } void perISBN(){ catalog *ptr; char isbn[20]; char ans; system("cls"); gotoxy(22,15); printf("Enter book ISBN: "); scanf("%s",isbn);fflush(stdin); ptr=root; while(ptr->isbn==isbn){ ptr=ptr->left; if(ptr==NULL) menu(); } system("cls"); if(ptr!=NULL){ gotoxy(22,10); printf("That book is in the catalog."); gotoxy(22,11); printf("Title: %s",ptr->title); gotoxy(22,12); printf("Author: %s",ptr->author); gotoxy(22,13); printf("ISBN: %d",ptr->isbn); gotoxy(22,14); printf("Genre: %s",ptr->genre); gotoxy(22,15); printf("Publisher: %s",ptr->publisher); gotoxy(22,16); printf("Year: %d",ptr->year); gotoxy(22,17); printf("Synopsis: %s",ptr->synopsis); } else { gotoxy(22,10); printf("No records to show..."); } printf("Try another? (y/n) "); scanf("%c",&ans); if(ans=='y' || ans=='Y'){ searchBook(); } getch(); menu(); } void perGenre(){ catalog *ptr; char genre[20],ans; char gen[10]; system("cls"); gotoxy(22,15); printf("Enter book title: "); scanf("%s",genre); ptr=root; while(strcmp(ptr->genre,genre)!=0){ ptr=ptr->left; if(ptr==NULL) menu(); } system("cls"); if(ptr!=NULL){ gotoxy(22,10); printf("That book is in the catalog."); gotoxy(22,11); printf("Title: %s",ptr->title); gotoxy(22,12); printf("Author: %s",ptr->author); gotoxy(22,13); printf("ISBN: %d",ptr->isbn); gotoxy(22,14); printf("Genre: %s",ptr->genre); gotoxy(22,15); printf("Publisher: %s",ptr->publisher); gotoxy(22,16); printf("Year: %d",ptr->year); gotoxy(22,17); printf("Synopsis: %s",ptr->synopsis); } else { gotoxy(22,10); printf("No records to show..."); } printf("Try another? (y/n) "); scanf("%c",&ans); switch(ans){ case 'y': searchBook(); break; case 'n': menu(); } } void displayCatalog(catalog *root){ catalog *ptr; system("cls"); fx=fopen("CAT.dat","rb+"); rewind(fx); ptr=root; while(fread(&ptr,structsize,1,fx)==1){ if(root->left!=NULL){ displayCatalog(root->left); } printf("Title: %s\n",ptr->title); printf("Author: %s\n",ptr->author); printf("ISBN: %s\n",ptr->isbn); printf("Genre: %s\n",ptr->genre); printf("Publisher: %s\n",ptr->publisher); printf("Year: %d\n",ptr->year); printf("Synopsis: %s\n",ptr->synopsis); if(root->right!=NULL){ displayCatalog(root->right); } break; } fclose(fx); getch(); menu(); } void gotoxy(int x,int y){ COORD coord; coord.X=x; coord.Y=y; SetConsoleCursorPosition(GetStdHandle(STD_OUTPUT_HANDLE), coord); }

Answer 1

1) 您已关闭所有编译器警告，或者您已选择忽略大约 100 个编译器警告。

您应该重新开始，将编译器警告设置为最大值，或至少 4。编写程序，使其在编译时出现零警告。

几个值得注意的错误：

scanf("%d",root->isbn);

isbn 是字符数组，所以这应该是 scanf("%s",root->isbn);

scanf("%d", root->year);

scanf 需要变量的地址，而不是复制。应该是scanf("%d", &root->year);

您还有许多其他错误，例如在 void modify 中您尝试访问未初始化的指针 ptr。

2) 你有这个 gotoxy 功能，它让事情看起来很不错，但你应该删除它，因为你的程序根本无法运行。如果您的程序可以正常运行，那么您可以放回这些修饰函数。

3) 尽量避免使用全局变量。 FILE *fx, *fy; 特意出问题。您有打开的文件句柄，然后您尝试以不同的模式再次打开它们。

catalog *root;没有分配。整个程序似乎都依赖于这个变量，这将无处可去。例如

void perTitle() 
{
    catalog *ptr;
    ...
    ptr = root;
    while (ptr != NULL) 
    {
        while (strcpy(temp, ptr->title)) 
        {
            ...
        }
    }
}

这可能看起来像一个搜索功能，但它只是 while(0){}，它什么也做不了。

4) 看来你是在管理文件中的记录，并且还把它们存储在一个链表中。这变得非常混乱。你应该做一个或另一个。我建议您将记录存储在文件中。将它们读入链表。然后在完成后将它们保存到文件中。

5) 使用更多的功能来避免输入同样的东西。例如写一个新函数 showBook

void showBook(catalog *ptr)
{
    printf("Title: %s\n", ptr->title);
    printf("Author: %s\n", ptr->author);
    printf("ISBN: %s\n", ptr->isbn);
    printf("Genre: %s\n", ptr->genre);
    printf("Publisher: %s\n", ptr->publisher);
    printf("Year: %d\n", ptr->year);
    printf("Synopsis: %s\n", ptr->synopsis); 
}

您可以在 perTitle()、perAuthor()、perISBN()、perGenre() 和其他地方重复使用此函数。

6) 初始化数据为零，例子：

catalog *ptr = malloc(sizeof(catalog));
memset(ptr, 0, sizeof(catalog));

从一个小程序开始。添加几个简单的功能，测试一下，添加更多功能。您可能想编写一个单独的测试程序来测试链表。例子

void getBook(catalog *ptr)
{
    printf("Title:\n");
    scanf("%s", ptr->title);
    printf("Author:\n");
    scanf("%s", ptr->author);
    printf("Genre:\n");
    scanf("%s", ptr->genre);
    printf("ISBN:\n");
    scanf("%s", ptr->isbn);
    printf("Publisher:\n");
    scanf("%s", ptr->publisher);
    printf("Year:\n");
    scanf("%d", &ptr->year);
    printf("Synopsis:\n");
    scanf("%s", ptr->synopsis);
}

void addBooks() 
{
    catalog cat;
    memset(&cat, sizeof(catalog), 0);
    getBook(&cat);
    FILE* fx = fopen("CAT.dat", "ab+");
    fseek(fx, 0, SEEK_END);
    fwrite(ptr, structsize, 1, fx);
    fclose(fx);
    printf("Add another (y/n)?\n");

    char n;
    scanf("%c", &n);
    if (n == 'y' || n == 'Y') 
        addBooks();

    _getch();
    menu();
}

void displayCatalog()
{
    system("cls");
    FILE* fx = fopen("CAT.dat", "rb+");
    catalog cat;
    while (fread(&cat, sizeof(catalog), 1, fx) == 1)
    {
        showBook(&cat);
        break;
    }
    fclose(fx);
    _getch();
    menu();
}

void menu() 
{
    int choice;
    system("cls");
    printf("----------WELCOME TO THE CARD CATALOG----------\n");
    printf("1] Add a book\n");
    printf("2] Remove a book\n");
    printf("3] Modify a book\n");
    printf("4] Search a book\n");
    printf("5] Display the catalog\n");
    printf("6] Exit\n");
    printf("Enter your choice: \n");
    scanf("%d", &choice);

    switch (choice) 
    {
    case 1: addBooks(); break;
    case 2: removeBooks(); break;
    case 3: modify(); break;
    case 4: searchBook(); break;
    case 5: displayCatalog(); break;
    case 6: exit(0);
    }
}

int main() 
{
    FILE *f = fopen("CAT.dat", "rb+");
    if (f == NULL)
    {
        f = fopen("CAT.dat", "wb+");
        if (f == NULL)
        {
            printf("Cannot create new file...\n");
            return 0;
        }
    }
    fclose(f);
    menu();
    return 0;
}

我在 C 代码中的错误是什么？这是一个需要使用 FILE 处理和 BST 的图书馆目录

What are my errors in this code in C? It's a library catalog that needs to use FILE handling and BST

c

file-handling

binary-search-tree

data-structures