结构体综合应用

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

#define MAXTITL 40 
#define MAXAUTL 40 
#define MAXBKS  10 

typedef struct book
{
    
    
    char title[MAXTITL];
    char author[MAXAUTL];
    float value;
}Book;

char* s_gets(char* st, int n)
{
    
    
    char* ret_val;
    char* find;

    ret_val = fgets(st,n,stdin);
    if(ret_val)
    {
    
    
        find = strchr(st,'\n');
        if(find)
            *find = '\0';
        else
            while (getchar() != '\n')          
                continue;
                   
    }
    return ret_val;

}


int main()
{
    
    
   Book library[MAXBKS];
   int count = 0;
   int index,filecount;

   FILE* pbook;
   int size = sizeof(Book);
   if((pbook = fopen("book.dat","a+b")) == NULL)
   {
    
    
       fputs("can't open book.dat file\n",stderr);
       exit(1);
   }
   rewind(pbook);

   while(count < MAXBKS && fread(&library[count],size,1,pbook) == 1 )
   {
    
    
       if(count == 0)
       puts("Current contents of book.dat:");
       printf("%s by %s: $%.2f\n",library[count].title,
       library[count].author,library[count].value);

       count++;

   }
   filecount = count;
   if(count == MAXBKS)
   {
    
    
       fputs("The book.dat file is full.",stderr);
       exit(2);
   }

   puts("Please add new book titles.");
   puts("Press [enter] at the start of a line to stop.");

    while (count < MAXBKS && s_gets(library[count].title,MAXTITL) != NULL
    && library[count].title[0] != '\0')
    {
    
    
        puts("Now enter the author.");
        s_gets(library[count].author,MAXAUTL);//输入字符串

        puts("Now enter the value.");
        scanf("%f",&library[count++].value);//输入数字

        while (getchar() != '\n')    //清理输入行      
            continue;

        if(count < MAXBKS)
            puts("Enter the next title.");

        if(count >0)
        {
    
    
            puts("Here is the list of your books:");
            for(index = 0;index < count; index++)
            printf("%s by %s: $%.2f\n",library[count].title,
            library[count].author,library[count].value);

            fwrite(&library[filecount],size,count - filecount,pbook);
        }

        fclose(pbook);

        return 0;

    }
    

   
   printf(" ");

   return 0;
}