c primer plus 习题答案(7)

p421.5

 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 }