#include<stdio.h>
float total(float a[],int n); //函数声明
float average(float a[],int n);
float highest(float a[],int n);
float lowest (float a[], int n);
voidmain()
{
float score[5];
int i;
printf("input scores of the subject_1 tosubject_5:\n");//进行五个数的输入
for(i=0;i<5;i++)
scanf("%f",&score);
printf("total=%5.2f\n",total(score,5));
printf("average=%5.2f\n",average(score,5));//这里是对怎么输出进行定义
printf("highest=%5.2f\n",highest(score,5));
printf("lowest=%5.2f\n",lowest(score,5));
}
float total(float s[],int n) //求总成绩，把各项数加起来，来求五项的和。
{
int i;
float sum=0;
for(i=0;i<n;i++) sum+=s;
return sum;
}
float average(float s[],int n) //求平均成绩，直接调用求平均数的函数。
{
return(total(s,5)/n);
}
float highest(float s[],int n) //最高成绩，每次比较把两个中最大的那个保留下来
{int i;
float max=s[0];
for(i=1;i<n;i++)
if(s>max) max=s;
return max;
}
float lowest(float s[],int n)//最低成绩
{
int i;
float min=s[0];
for(i=1;i<n;i++)
if(s<min) min=s;//通过比较，把最小的那个保留下来
return min;
}

怎么提示的呢？

#include<stdio.h>
float total(float a[],int n); //函数声明
float average(float a[],int n);
float highest(float a[],int n);
float lowest (float a[], int n);
main()
{
   float score[5];
   int i;
   printf("input scores of the subject_1 tosubject_5:\n");
   for(i=0;i<5;i++)
      scanf("%f",&score[i]); //应该是这样
   printf("total=%5.2f\n",total(score,5));
   printf("average=%5.2f\n",average(score,5));
   printf("highest=%5.2f\n",highest(score,5));
   printf("lowest=%5.2f\n",lowest(score,5));

}
float total(float s[],int n)
{
   int i;
   float sum=0;
   for(i=0;i<n;i++) sum+=s[i]; //应该是这样
   return sum;
}
float average(float s[],int n)  
{
   return(total(s,5)/n);
}
float highest(float s[],int n)  
{
   int i;
   float max=s[0];
   for(i=1;i<n;i++)
   if(s[i]>max) max=s[i]; //应该是这样
   return max;
}
float lowest(float s[],int n)
{
   int i;
   float min=s[0];
   for(i=1;i<n;i++)
   if(s[i]<min) min=s[i];//应该是这样
   return min;
}