例4--2

#include<stdio.h> int main(void) {  int count,num;  double grade,total;

 num=0;  total=0;  count=0;  printf("Enter grades:");  scanf("%lf",&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);  }  else   printf("Grade average is0\n");  return 0; }