修改下面的书目列表程序，使它首先按照输入的顺序输出图书的描述，然后按照标题的字母升序输出图书的描述，最后按照value值的升序输出图书的描述。
/* manybook.c -- 包含多本书的图书目录 */
#include <stdio.h>
#define MAXTITL 40
#define MAXAUTL 40
#define MAXBKS 100 /* 最多可以容纳的图书册数 */
struct book { /* 建立book模板 */
char title[MAXTITL];
char author[MAXAUTL];
float value;
};
int main(void)
{
struct book library[MAXBKS]; /* book结构数组 */
int count = 0;
int index;
printf("Please enter the book title.\n");
printf("Press [enter] at the start of a line to stop.\n");
while(count < MAXBKS && gets (library[count].title) != NULL
&& library[count].title[0] != '\0')
{
printf("Now enter the author.\n");
gets(library[count].author);
printf("Now enter the value.\n");
scanf("%f, &library[count++].value);
while(getchar() != '\n')
continue; /* 清空输入行 */
if(count < MAXBKS)
printf("Enter the next title.\n");
}
if (count>0)
{
printf("Here is the list of your books: \n");
for(index = 0; index < count; index++)
printf("%s by %s: $%.2f\n", library[index].title,
library[index].author, library[index].value);
}
if (count>0)
{
printf("Here is the list of your books: \n");
for(index = 0; index < count; index++)
printf("%s by %s: $%.2f\n", library[index].title,
library[index].author, library[index].value);
}
else
printf("No books?Too bad.\n");
return 0;
}
#include <stdio.h> #include <string.h> void sort_title(struct book *p, int count); void sort_value(struct book *p, int count); #define MAXTITL 40 #define MAXAUTL 40 #define MAXBKS 100 /* maximum number of books */ struct book { /* set up book template */ char title[MAXTITL]; char author[MAXAUTL]; float value; }; int main(void) { struct book library[MAXBKS]; /* array of book structures */ int count = 0; int index; printf("Please enter the book title.\n"); printf("Press [enter] at the start of a line to stop.\n"); while (count < MAXBKS && gets(library[count].title) != NULL && library[count].title[0] != '\0') { printf("Now enter the author.\n"); gets(library[count].author); printf("Now enter the value.\n"); scanf("%f", &library[count++].value); while (getchar() != '\n') continue; /* clear input line */ if (count < MAXBKS) printf("Enter the next title.\n"); } if (count > 0) { printf("Here is the list of your books:\n"); for (index = 0; index < count; index++) printf("%s by %s: $%.2f\n", library[index].title, library[index].author, library[index].value); printf("\nHere is the list of your books by title:\n"); sort_title(&library[0], count); for (index = 0; index < count; index++) printf("%s by %s: $%.2f\n", library[index].title, library[index].author, library[index].value); printf("\nHere is the list of your books by value:\n"); sort_value(&library[0], count); for (index = 0; index < count; index++) printf("%s by %s: $%.2f\n", library[index].title, library[index].author, library[index].value); } else printf("No books? Too bad.\n"); return 0; } void sort_title(struct book *p, int count) { int i,j; struct book temp; for(i=0; i<count-1; i++) for(j=0; j<count-1-i; j++) if( strcmp(p[j].title,p[j+1].title) > 0 ) { temp = p[j] ; p[j] = p[j+1] ; p[j+1] = temp ; } } void sort_value(struct book *p, int count) { int i,j; struct book temp; for(i=0; i<count-1; i++) for(j=0; j<count-1-i; j++) if( p[j].value > p[j+1].value ) { temp = p[j] ; p[j] = p[j+1] ; p[j+1] = temp ; } }