>>147
問題1

#include <stdio.h>
int main(void)
{
double v[5] = {0.0};
int i = 0, j;
double sum;

while (1) {
printf("input: "); scanf("%lf", &v[i%5]);
if (v[i%5] < 0) {
break;
}
sum = 0.0;
for (j = 0; j < 5; j++) {
sum += v[j];
}
printf("sum: %f\n", sum);
printf("average: %f\n", sum / 5);
i++;
}
return 0;
}