第四章2

#include<stdio.h>
int main(void)
{
    int count,num;
    double grade,total;
    
    num=0;
    total=0;
    count=0;
    printf("Enter grade:");
    scanf("%lf\n",&grade);
    
    while(grade>=0){
        total=total+grade;
        num++;
        if(grade<60)
            count++;
        scanf("%lf",&grade);
    }
    if(num!=0){
        printf("grade average is %.2f\n",total/num);
        printf("number of failures is %d",count);
    }
    else
        printf("grade average is 0\n");
        
    return 0;
}