用C语言完成：采用结构体数组对学生的学号、姓名、各科成绩的存储，按成绩排序，按学号、姓名查找

好的，以下是用C语言实现对学生信息的存储、排序和查找的代码：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define MAX_STUDENT 100 // 最大学生数

// 学生结构体
struct student {
    int id; // 学号
    char name[20]; // 姓名
    float score[3]; // 三科成绩
    float total; // 总分
};

// 学生数组
struct student students[MAX_STUDENT];

// 学生数
int num_students = 0;

// 比较函数：按总分排序
int cmp_by_total(const void *a, const void *b) {
    struct student *s1 = (struct student *)a;
    struct student *s2 = (struct student *)b;
    return (s2->total - s1->total) > 0 ? 1 : -1;
}

// 比较函数：按学号排序
int cmp_by_id(const void *a, const void *b) {
    struct student *s1 = (struct student *)a;
    struct student *s2 = (struct student *)b;
    return s1->id - s2->id;
}

// 比较函数：按姓名排序
int cmp_by_name(const void *a, const void *b) {
    struct student *s1 = (struct student *)a;
    struct student *s2 = (struct student *)b;
    return strcmp(s1->name, s2->name);
}

// 添加学生
void add_student() {
    if (num_students >= MAX_STUDENT) {
        printf("已达到最大学生数，无法添加！\n");
        return;
    }
    printf("请输入学号：");
    scanf("%d", &students[num_students].id);
    printf("请输入姓名：");
    scanf("%s", students[num_students].name);
    printf("请输入三科成绩（用空格分隔）：");
    scanf("%f %f %f", &students[num_students].score[0], &students[num_students].score[1], &students[num_students].score[2]);
    students[num_students].total = students[num_students].score[0] + students[num_students].score[1] + students[num_students].score[2];
    num_students++;
    printf("添加成功！\n");
}

// 显示学生信息
void show_students() {
    if (num_students == 0) {
        printf("学生信息为空！\n");
        return;
    }
    printf("学号\t姓名\t成绩1\t成绩2\t成绩3\t总分\n");
    for (int i = 0; i < num_students; i++) {
        printf("%d\t%s\t%.1f\t%.1f\t%.1f\t%.1f\n", students[i].id, students[i].name, students[i].score[0], students[i].score[1], students[i].score[2], students[i].total);
    }
}

// 按总分排序
void sort_by_total() {
    qsort(students, num_students, sizeof(struct student), cmp_by_total);
    printf("按总分排序成功！\n");
}

// 按学号排序
void sort_by_id() {
    qsort(students, num_students, sizeof(struct student), cmp_by_id);
    printf("按学号排序成功！\n");
}

// 按姓名排序
void sort_by_name() {
    qsort(students, num_students, sizeof(struct student), cmp_by_name);
    printf("按姓名排序成功！\n");
}

// 按学号查找
void search_by_id() {
    int id;
    printf("请输入要查找的学号：");
    scanf("%d", &id);
    for (int i = 0; i < num_students; i++) {
        if (students[i].id == id) {
            printf("学号\t姓名\t成绩1\t成绩2\t成绩3\t总分\n");
            printf("%d\t%s\t%.1f\t%.1f\t%.1f\t%.1f\n", students[i].id, students[i].name, students[i].score[0], students[i].score[1], students[i].score[2], students[i].total);
            return;
        }
    }
    printf("未找到该学生！\n");
}

// 按姓名查找
void search_by_name() {
    char name[20];
    printf("请输入要查找的姓名：");
    scanf("%s", name);
    for (int i = 0; i < num_students; i++) {
        if (strcmp(students[i].name, name) == 0) {
            printf("学号\t姓名\t成绩1\t成绩2\t成绩3\t总分\n");
            printf("%d\t%s\t%.1f\t%.1f\t%.1f\t%.1f\n", students[i].id, students[i].name, students[i].score[0], students[i].score[1], students[i].score[2], students[i].total);
            return;
        }
    }
    printf("未找到该学生！\n");
}

int main() {
    int choice;
    while (1) {
        printf("\n");
        printf("1. 添加学生\n");
        printf("2. 显示学生信息\n");
        printf("3. 按总分排序\n");
        printf("4. 按学号排序\n");
        printf("5. 按姓名排序\n");
        printf("6. 按学号查找\n");
        printf("7. 按姓名查找\n");
        printf("8. 退出\n");
        printf("请选择操作：");
        scanf("%d", &choice);
        switch (choice) {
            case 1:
                add_student();
                break;
            case 2:
                show_students();
                break;
            case 3:
                sort_by_total();
                break;
            case 4:
                sort_by_id();
                break;
            case 5:
                sort_by_name();
                break;
            case 6:
                search_by_id();
                break;
            case 7:
                search_by_name();
                break;
            case 8:
                printf("再见！\n");
                return 0;
            default:
                printf("无效的选择！\n");
                break;
        }
    }
    return 0;
}

该程序使用结构体数组存储学生信息，支持添加、显示、排序和查找操作。可以按学号、姓名或总分进行排序，按学号或姓名进行查找。