>>493
#include<stdio.h>
#include<stdlib.h>

typedef struct tag_student_t{
int id, score[3];
}student_t;

double average(student_t *student){
double ave=0.0;
int i;

for(i=0;i<3;i++) ave=(ave*i+student->score[i])/(i+1);
return ave;
}

int main(void){
student_t student[5];
int i, j;

for(i=0;i<5;i++){
student[i].id=i+1;
for(j=0;j<3;j++) student[i].score[j]=rand()%101;
}
for(i=0;i<5;i++){
printf("\nid:%d average:%-6.2f", student[i].id, average(&student[i]));
for(j=0;j<3;j++) printf(" %3d", student[i].score[j]);
}
return 0;
}