C //习题 7.14 输入10个学生5门课的成绩，分别用函数实现下列功能：1.计算每个学生的平均分；2.计算每门课的平均分；3.找出所有50个分数中最高的分数所对应的学生和课程；4.计算平均分方差。

在C语言中，你可以按照以下步骤编写程序来完成这个习题：

#include <stdio.h>
#include <string.h> // 用于处理字符串

// 结构体表示一个学生及其成绩
typedef struct {
    char name[50];
    int scores[5]; // 学生五门课的成绩
} Student;

// 计算学生的平均分
float student_average(Student student) {
    float sum = 0;
    for (int i = 0; i < 5; i++) {
        sum += student.scores[i];
    }
    return sum / 5.0;
}

// 计算每门课的平均分
void course_average(int *scores, int num_students) {
    float total = 0;
    for (int i = 0; i < num_students; i++) {
        total += scores[i];
    }
    printf("平均分：%.2f\n", total / num_students);
}

// 找出最高分的学生和课程
void find_highest_score(Student students[], int num_students) {
    int highest_score = students[0].scores[0], max_index = 0;
    for (int i = 0; i < num_students; i++) {
        for (int j = 0; j < 5; j++) {
            if (students[i].scores[j] > highest_score) {
                highest_score = students[i].scores[j];
                max_index = i;
            }
        }
    }
    printf("最高分学生：%s, 最高分课程：%d\n", students[max_index].name, max_index);
}

// 计算方差
double variance(Student students[], int num_students) {
    double mean = 0;
    for (int i = 0; i < num_students; i++) {
        mean += student_average(students[i]);
    }
    mean /= num_students;
    
    double sum_of_squares = 0;
    for (int i = 0; i < num_students; i++) {
        sum_of_squares += pow(student_average(students[i]) - mean, 2);
    }

    return sum_of_squares / num_students;
}

int main() {
    Student students[10];
    for (int i = 0; i < 10; i++) {
        scanf("%s", students[i].name);
        for (int j = 0; j < 5; j++) {
            scanf("%d", &students[i].scores[j]);
        }
    }

    // 使用函数计算并打印结果
    for (int i = 0; i < 10; i++) {
        printf("学生 %s 的平均分：%.2f\n", students[i].name, student_average(students[i]));
    }
    
    course_average(students[0].scores, 10);

    find_highest_score(students, 10);
    
    double overall_variance = variance(students, 10);
    printf("整体平均分方差：%.2f\n", overall_variance);

    return 0;
}