第四章例4-2

/* 输入一批学生的成绩，以负数作为结束标志，计算平均成绩，并统计不及格人数 */
#include<stdio.h>
int main(void)
{int count,num;double grade,total;num=0;total=0;count=0;printf("Enter grades:");scanf_s("%lf",&grade);while(grade>=0){total=total+grade;num++;if(grade<60)count++;scanf_s("%lf",&grade);}if(num!=0){printf("Grade average is %.2f\n",total/num);printf("Number of failures is %d\n",count);}elseprintf("Grade average is 0\n");return 0;
}