提高篇第22-25课第二题

#include <stdio.h>
#include <stdlib.h>
#include <math.h>
//第二题
void input_score(int s[], int n); //将小组中n名同学的成绩输入数组s
int get_max_score(int s[], int n);  //返回数组s中n名同学的最高成绩值
int get_min_score(int s[], int n);  //返回数组s中n名同学的最低成绩值
double get_avg_score(int s[], int n);  //返回数组s中n名同学的平均成绩值
double get_stdev_score(int s[], int n); //返回数组s中n名同学成绩值的标准偏差
int count(int x, int s[], int n);  //返回在数组s中n名同学中有多少人得x分（实参给出最高/低时，可以求最高/低成绩的人数）
void output_index(int x, int s[], int n); //在函数中输出数组s中n名同学中得x分的学号（下标）

int main()
{
	int score[50]; //将score设为局部变量，通过数组名作函数参数，传递数组首地址，在函数中操作数组
	int num;       //小组人数也设为局部变量，将作为函数的实际参数
	int max_score, min_score;
	printf("小组共有多少名同学? ");
	scanf("%d", &num);
	printf("请输入学生成绩：\n");
	input_score(score, num);  //要求成绩在0-100之间
	max_score = get_max_score(score, num);
	printf("最高成绩为：%d，共有 %d 人\n", max_score, count(max_score, score, num));
	min_score = get_min_score(score, num);
	printf("最低成绩为：%d，共有 %d 人\n", min_score, count(min_score, score, num));
	printf("平均成绩为：%.2f\n", get_avg_score(score, num));
	printf("标准偏差为：%.2f\n", get_stdev_score(score, num));
	printf("获最高成绩的学生(学号)有：");
	output_index(max_score, score, num);
	printf("\n获最低成绩的学生(学号)有：");
	output_index(min_score, score, num);
	printf("\n");
	return 0;
}
void input_score(int s[], int n)
{
	int i;
	for (i = 0; i < n; i++)
		scanf("%d", s + i);
}
int get_max_score(int s[], int n)
{
	int max=s[0];
	int i;
	for (i = 0; i < n; i++)
	{
		if (s[i] >= max)
			max = s[i];
	}
	return max;
}
int get_min_score(int s[], int n)
{
	int min = s[0];
	int i;
	for (i = 0; i < n; i++)
	{
		if (s[i] <= min)
			min = s[i];
	}
	return min;
}
double get_avg_score(int s[], int n)
{
	int sum = 0;
	int i;
	double avg;
	for (i = 0; i < n; i++)
		sum += s[i];
	avg = sum / n;
	return avg;
}
double get_stdev_score(int s[], int n)
{
	int i;
	double avg;
	double temp_sum=0,stdev;
	avg = get_avg_score(s, n);
	for (i = 0; i < n; i++)
		temp_sum += (s[i] - avg)*(s[i] - avg);
	stdev = sqrt(temp_sum / (n - 1));
	return stdev;
}
int count(int key, int s[], int n)
{
	int count = 0,i;
	for (i = 0; i < n; i++)
		if (s[i] == key)
			count++;
	return count;
}
void output_index(int key, int s[], int n)
{
	int i;
	for (i = 0; i < n; i++)
		if (s[i] == key)
			printf("%d,", i);
}