用结构体和指针编程。某班有5名学生，每名学生的数据包括学号、姓名、3 门课程的成绩。从键盘输入5名学生数据，输出5名同学平均成绩， 以及平均分最高的学生的数据（包括学号、姓名、 3 门课成绩、平均成绩）。

以下是使用结构体和指针编写的代码：

#include <stdio.h>

#define NUM_OF_STUDENTS 5
#define NUM_OF_COURSES 3

struct student {
    int id;
    char name[20];
    int scores[NUM_OF_COURSES];
    float avg_score;
};

void input_students(struct student *students, int num);
void calc_avg_score(struct student *students, int num);
struct student *find_highest_avg_score(struct student *students, int num);

int main() {
    struct student students[NUM_OF_STUDENTS];
    input_students(students, NUM_OF_STUDENTS);
    calc_avg_score(students, NUM_OF_STUDENTS);
    struct student *highest_avg_score_student = find_highest_avg_score(students, NUM_OF_STUDENTS);
    printf("Average score of all students: %.2f\n", students[0].avg_score);
    printf("Student with highest average score:\n");
    printf("ID: %d\n", highest_avg_score_student->id);
    printf("Name: %s\n", highest_avg_score_student->name);
    printf("Scores: ");
    for (int i = 0; i < NUM_OF_COURSES; i++) {
        printf("%d ", highest_avg_score_student->scores[i]);
    }
    printf("\nAverage score: %.2f\n", highest_avg_score_student->avg_score);
    return 0;
}

void input_students(struct student *students, int num) {
    for (int i = 0; i < num; i++) {
        printf("Enter information for student %d:\n", i + 1);
        printf("ID: ");
        scanf("%d", &students[i].id);
        printf("Name: ");
        scanf("%s", students[i].name);
        for (int j = 0; j < NUM_OF_COURSES; j++) {
            printf("Score for course %d: ", j + 1);
            scanf("%d", &students[i].scores[j]);
        }
    }
}

void calc_avg_score(struct student *students, int num) {
    for (int i = 0; i < num; i++) {
        float sum = 0;
        for (int j = 0; j < NUM_OF_COURSES; j++) {
            sum += students[i].scores[j];
        }
        students[i].avg_score = sum / NUM_OF_COURSES;
    }
}

struct student *find_highest_avg_score(struct student *students, int num) {
    struct student *highest_avg_score_student = &students[0];
    for (int i = 1; i < num; i++) {
        if (students[i].avg_score > highest_avg_score_student->avg_score) {
            highest_avg_score_student = &students[i];
        }
    }
    return highest_avg_score_student;
}

首先定义了一个 `student` 结构体，包含学号、姓名、3门成绩和平均成绩。然后定义了三个函数：

- `input_students`：从键盘输入学生信息。
- `calc_avg_score`：计算每个学生的平均成绩。
- `find_highest_avg_score`：找出平均分最高的学生。

在 `main` 函数中，先调用 `input_students` 和 `calc_avg_score` 函数，然后调用 `find_highest_avg_score` 函数找到平均分最高的学生，最后输出所有学生的平均成绩和平均分最高的学生的信息。