c primer plus 习题答案(7)

 1 #include<stdio.h>
 2 #include<stdlib.h>
 3 #define CSIZE 4
 4 #define SCORE 3
 5 
 6 void get_info(struct students *p);
 7 void get_average(struct students *p);
 8 void print_info(struct students *p);
 9 void print_class_average(struct students *p);
10 
11 struct names{
12     char firstname[40];
13     char lastname[40];
14 };
15 
16 struct students{
17     struct names name;
18     float grade[SCORE];
19     float average;
20 };
21 
22 int main(void)
23 {
24     struct students sheet[CSIZE]={
25         {{"absbs", "bdcdc"}, 0, 0, 0, 0},
26         {{"cfvfv", "dfgfg"}, 0, 0, 0, 0},
27         {{"enmnm", "fcvcv"}, 0, 0, 0 ,0},
28         {{"ghbhb", "hiyiy"}, 0, 0, 0, 0}
29     };
30 
31 
32     get_info(sheet);
33     get_average(sheet);
34     print_info(sheet);
35     print_info(sheet);
36 
37     system("pause");
38     return 0;
39 }
40 
41 void get_info(struct students *p)
42 {
43     int i,j;
44     for(i=0; i<CSIZE; i++){
45         puts("please input student name");
46         scanf("%s%s",&((p+i)->name.firstname),&((p+i)->name.lastname));
47         puts("input the score");
48         for(j=0; j<SCORE; j++)
49             scanf("%f",&((p+i)->grade[j]));
50     }
51 }
52 
53 void get_average(struct students *p)
54 {
55     float sum; 
56     int i, j;
57     for(i=0; i<CSIZE; i++){
58         for(j=0, sum=0; j<SCORE; j++)
59         sum+=((p+i)->grade[j]);
60         (p+i)->average=sum/SCORE;
61     }
62 }
63 
64 void print_info(struct students *p)
65 {
66     int i, j;
67     for(i=0; i<CSIZE; i++){
68         printf("%s\t%s\n", (p+i)->name.firstname, (p+i)->name.lastname);
69         printf("grade:\n");
70         for(j=0; j<SCORE; j++)
71             printf("%f ",(p+i)->grade[j]);
72         printf("\n");
73         printf("the average grade is %.2f", (p+i)->average);
74     }
75 }
76 
77 void print_class_average(struct students *p)
78 {
79     int i;
80     float sum=0;
81 
82     for(i=0; i<CSIZE; i++)
83         sum+=(p+i)->average;
84 
85     printf("the class average grade is %.2f", sum/CSIZE);
86 }