Question

我是这个网站的新手，看起来很酷。

我有这个问题，我想创建一个程序，用户决定要声明多少本书，然后用户填写所请求的每本书的信息（例如：用户想要3本书，所以他填写了所有的信息这3本书）。

我想我需要一个数组结构，但我不知道如何循环这个填充过程。

这是我的代码：

struct book
    {
    char bname[20];
    int pages;
    char author[20];
    long price; 
};

printf("enter number of books to store");
scanf("%d",&unumber);
for (i=0;i<number_of_books;i++) {printf's and scanf's to fill each struct}

Answer 1

有两种方法可以做到这一点。一个是简单的使用图书结构的数组另一个使用链表。下面，我给你两个解决方案：

使用结构数组的第一个解决方案：

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

#define MAXBOOKS 100

struct book {
     char bname[20];
     int pages;
     char author[20];
     long price;
};

int main()
{
     struct book books[MAXBOOKS];
     int number_of_books;
     printf("enter number of books to store\n");
     scanf("%d",&number_of_books);

     // writing books
     for (int i=0;i<number_of_books;i++) {
            printf("Enter new book record: Book_Name, Pages, Author, Price\n");
            scanf("%s %d %s %ld",books[i].bname, &books[i].pages, books[i].author, &books[i].price);

     }


     //reading books
     printf("Entered books records: Book_Name, Pages, Author, Price\n");
     for (int i=0;i<number_of_books;i++) {
            printf("%s\t %d\t %s\t %ld\n",books[i].bname, books[i].pages, books[i].author, books[i].price);

     }

     return 0;
 }

使用关联列表的第二个解决方案： 您可以将所有图书存储为链接列表。添加一个额外的数据字段，然后指向下一个节点簿。

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

struct book { 
      char bname[20];
      int pages; 
      char author[20];
      long price; 
      struct book *next; 
};

int main()
{
     int number_of_books;
     printf("enter number of books to store");
     scanf("%d",&number_of_books);
     struct book *head, *temp,*curnode;
     head=NULL;
     temp=NULL;
     for (int i=0;i<number_of_books;i++) {
         // writing books
         temp=(struct book *)malloc(sizeof(struct book));
         printf("Enter new book record: Book_Name, Pages, Author, Price\n");
         scanf("%s %d %s %ld",temp->bname, &temp->pages, temp->author, &temp->price);
         temp->next=NULL;
         if(head==NULL){
             printf("in head if");
             head=temp;
             curnode=temp;
         } else {
             curnode->next=temp;
             curnode=curnode->next;
      }
   }


     //reading books
     temp=head;
     while(temp!=NULL){
         printf("%s\t %d\t %s\t %ld",temp->bname, temp->pages, temp->author, temp->price);
         printf("\n");

         temp=temp->next;

      }

return 0;
}

Answer 2

在循环中读取输入时，一个主要关注点是确保在每次读取后刷新stdin以防止尾随newline被解释为下一个read语句的输入。有很多方法可以做到这一点，但是，使用scanf最简单的方法是通过精心设计的format语句来消耗尾随newline。以下说明了这种方法：

#include <stdio.h>

#define MAXS 256

struct book
{
    char bname[20];
    int pages;
    char author[20];
    long price; 
};

int main () {

    struct book books[MAXS] = {{ {0}, 0, {0}, 0 }}; /* initialize all values to zero (null) */
    int nbooks = 0;
    int i = 0;

    printf ("\nEnter number of books to store: ");
    scanf("%d%*c",&nbooks);                         /* read nbooks, and consume newline     */

    if (nbooks < 1) {                               /* validate number of books to enter    */
        fprintf (stderr, "error: invalid entry for 'nbooks'\n");
        return 1;
    }

    for (i = 0; i < nbooks; i++)                    /* enter values for each book, use      */
    {                                               /* scanf to read each value AND the     */
        printf ("\n  book[%2d] name  : ", i + 1);   /* newline character, emptying stdin    */
        scanf ("%[^\n]%*c", books[i].bname);        /* after each read.                     */
        printf ("  book[%2d] pages : ", i + 1);
        scanf ("%d%*c", &books[i].pages);
        printf ("  book[%2d] author: ", i + 1);
        scanf ("%[^\n]%*c", books[i].author);
        printf ("  book[%2d] price : ", i + 1);
        scanf ("%ld%*c", &books[i].price);
    }

    printf ("\n\nThe Books Entered Were:\n");       /* output info for each book entered    */
    i = 0;
    while (*books[i].bname)
    {
        printf ("\n  Book %-3d \"%s\"\n", i + 1, books[i].bname);
        printf ("    author : %s\n", books[i].author);
        printf ("    pages  : %d\n", books[i].pages);
        printf ("    price  : %ld\n", books[i].price);
        i++;
    }

    printf ("\n");

    return 0;
}

<强>输出：

$ ./bin/books

Enter number of books to store: 2

  book[ 1] name  : Tom Sawyer
  book[ 1] pages : 321
  book[ 1] author: Mark Twain
  book[ 1] price : 2199

  book[ 2] name  : Huckelberry Finn
  book[ 2] pages : 298
  book[ 2] author: Mark Twain
  book[ 2] price : 1999


The Books Entered Were:

  Book 1   "Tom Sawyer"
    author : Mark Twain
    pages  : 321
    price  : 2199

  Book 2   "Huckelberry Finn"
    author : Mark Twain
    pages  : 298
    price  : 1999

如何用cycle-for和scanf填充我的结构数组的每个结构？

2 个答案: