1 /*-----------------------------------------
2 booksave.c -- 在文件中保存结构中的内容
3 -----------------------------------------*/
4
5 #include <stdio.h>
6 #include <stdlib.h>
7 #include <string.h>
8
9 #define MAXTITL 40
10 #define MAXAUTL 40
11 #define MAXBKS 10 //最大书籍数量
12
13 char* s_gets(char *st, int n);
14
15 struct book
16 {
17 char title[MAXTITL];
18 char author[MAXAUTL];
19 float value;
20 };
21
22 int main()
23 {
24 struct book library[MAXBKS];
25 int index, filecount;
26 FILE *pbooks;
27
28 if ((pbooks = fopen("book.dat", "a+b")) == NULL)
29 {
30 fputs("Can't open book.dat file\n", stderr);
31 exit(EXIT_FAILURE);
32 }
33
34 rewind(pbooks); //定位到文件开始
35
36 int count = 0, size = sizeof(struct book);
37
38 while (count != MAXBKS && fread(&library[count], size, 1, pbooks) == 1)
39 {
40 if (count == 0)
41 puts("Current contents of book.dat:");
42
43 printf("%s by %s: $%.2f\n"
44 , library[count].title, library[count].author, library[count].value);
45
46 ++count;
47 }
48
49 filecount = count;
50
51 if (count == MAXBKS)
52 {
53 fputs("The book.dat file is full.", stderr);
54 exit(2);
55 }
56
57 puts("Please add new book titles.");
58 puts("Press [enter] at the start of a line to stop.");
59
60 while (count != MAXBKS && s_gets(library[count].title, MAXTITL) != NULL
61 && library[count].title[0] != '\0')
62 {
63 puts("Now enter the author.");
64
65 s_gets(library[count].author, MAXAUTL);
66
67 puts("Now enter the value.");
68
69 scanf("%f", &library[count++].value);
70
71 while (fgetc(stdin) != '\n') continue; //清理输入行
72
73 if (count != MAXBKS)
74 puts("Enter the next title.");
75 }
76
77 if (count > 0)
78 {
79 puts("Here is the list of your books:");
80
81 for (index = 0; index != count; ++index)
82 printf("%s by %s: $%.2f\n"
83 , library[index].title, library[index].author, library[index].value);
84
85 fwrite(&library[filecount], size, count - filecount, pbooks);
86 }
87 else
88 puts("No books? Too bad.\n");
89
90 puts("Bye.\n");
91 fclose(pbooks);
92
93 return 0;
94 }
95
96 char* s_gets(char *st, int n)
97 {
98 char *ret_val, *find;
99
100 if (ret_val = fgets(st, n, stdin))
101 {
102 if (find = strchr(st, '\n'))
103 *find = '\0';
104 else
105 while (fgetc(stdin) != '\n') continue;
106 }
107
108 return ret_val;
109 }
