编辑代码

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

typedef struct student{
    char name[20];
    int id;
    char dormitory[20];
    char qq[20];
    char phone[20];
    int cet4_score;
} Student;

#define MAX_STUDENT_NUM 100 //定义最大保存的学生数量
Student students[MAX_STUDENT_NUM]; //定义保存学生信息的数组
int student_num = 0; //已保存学生数量

//比较函数，用于按姓名升序排序
int cmp_by_name(const void *a, const void *b) {
    return strcmp(((Student*)a)->name, ((Student*)b)->name);
}

//比较函数，用于按电话号码升序排序
int cmp_by_phone(const void *a, const void *b) {
    return strcmp(((Student*)a)->phone, ((Student*)b)->phone);
}

//添加学生信息
void add_student() {
    if (student_num >= MAX_STUDENT_NUM) {
        printf("Error: 学生数量已达到上限\n");
        return;
    }
    Student new_student;
    printf("请输入学生姓名：");
    scanf("%s", new_student.name);
    printf("请输入学生学号：");
    scanf("%d", &new_student.id);
    printf("请输入学生宿舍：");
    scanf("%s", new_student.dormitory);
    printf("请输入学生QQ号：");
    scanf("%s", new_student.qq);
    printf("请输入学生电话：");
    scanf("%s", new_student.phone);
    printf("请输入学生CET4成绩：");
    scanf("%d", &new_student.cet4_score);

    students[student_num++] = new_student;
    printf("已添加学生 %s 的信息\n", new_student.name);
}

//删除学生信息
void delete_student() {
    printf("请输入要删除的学生姓名：");
    char name_to_delete[20];
    scanf("%s", name_to_delete);

    int deleted_num = 0;
    for (int i = 0; i < student_num; i++) {
        if (strcmp(name_to_delete, students[i].name) == 0) {
            //将被删除的学生信息覆盖，然后将数组前移
            deleted_num++;
            if (i != student_num-1) {
                memcpy(&students[i], &students[i+1], sizeof(Student)*(student_num-i-1));
            }
        }
    }
    student_num -= deleted_num;

    printf("已删除 %d 名学生的信息\n", deleted_num);
}

//按照姓名升序排序并打印
void sort_and_print_by_name() {
    qsort(students, student_num, sizeof(Student), cmp_by_name);
    for (int i = 0; i < student_num; i++) {
    printf("姓名：%s\n", students[i].name);
    printf("学号：%d\n", students[i].id);
    printf("宿舍：%s\n", students[i].dormitory);
    printf("QQ号：%s\n", students[i].qq);
    printf("电话：%s\n", students[i].phone);
    printf("CET4 成绩：%d\n", students[i].cet4_score);
    printf("\n"); // 输出一个空行，以区分下一个学生
    }
}

//按照电话号码升序排序并打印
void sort_and_print_by_phone() {
    qsort(students, student_num, sizeof(Student), cmp_by_phone);
    for (int i = 0; i < student_num; i++) {
    printf("姓名：%s\n", students[i].name);
    printf("学号：%d\n", students[i].id);
    printf("宿舍：%s\n", students[i].dormitory);
    printf("QQ号：%s\n", students[i].qq);
    printf("电话：%s\n", students[i].phone);
    printf("CET4 成绩：%d\n", students[i].cet4_score);
    printf("\n"); // 输出一个空行，以区分下一个学生
    }
}

//按姓名查找电话号码
void find_phone_by_name() {
    printf("请输入要查询的学生姓名：");
    char name_to_find[20];
    scanf("%s", name_to_find);

    int found_num = 0;
    for (int i = 0; i < student_num; i++) {
        if (strcmp(name_to_find, students[i].name) == 0) {
            printf("%s 的电话是 %s\n", name_to_find, students[i].phone);
            found_num++;
        }
    }

    if (found_num == 0) {
        printf("没有找到姓名为 %s 的学生信息\n", name_to_find);
    }
}

//按电话号码查找姓名
void find_name_by_phone() {
    printf("请输入要查询的学生电话：");
    char phone_to_find[20];
    scanf("%s", phone_to_find);

    int found_num = 0;
    for (int i = 0; i < student_num; i++) {
        if (strcmp(phone_to_find, students[i].phone) == 0) {
            printf("%s 的姓名是 %s\n", phone_to_find, students[i].name);
            found_num++;
        }
    }

    if (found_num == 0) {
        printf("没有找到电话为 %s 的学生信息\n", phone_to_find);
    }
}
void cet_statistics() {
    // 统计 CET 成绩信息
    double sum = 0;
    int pass_count = 0;
    for (int i = 0; i < student_num; i++) {
        sum += students[i].cet4_score;
        if (students[i].cet4_score >= 425) {
            pass_count++;
        }
    }
    double average = sum / student_num;
    double variance = 0;
    for (int i = 0; i < student_num; i++) {
       variance += (students[i].cet4_score - average) * (students[i].cet4_score - average);
    }
    variance /= student_num;

    printf("平均成绩：%.2lf\n", average);
    printf("方差：%.2lf\n", variance);
    printf("及格率：%.2lf%%\n", ((double)pass_count / student_num) * 100);
}

//打印菜单
void print_menu() {
    printf("请选择操作：\n");
    printf("1. 添加学生信息\n");
    printf("2. 删除学生信息\n");
    printf("3. 打印所有学生信息并按照姓名排序\n");
    printf("4. 打印所有学生信息并按照电话号码排序\n");
    printf("5. 按姓名查找电话号码\n");
    printf("6. 按电话号码查找姓名\n");
    printf("7. 分析四级成绩\n");
}

int main() {
    while (1) {
        print_menu();
        int option;
        scanf("%d", &option);
        switch (option) {
            case 1:
                add_student();
                break;
            case 2:
                delete_student();
                break;
            case 3:
                sort_and_print_by_name();
                break;
            case 4:
                sort_and_print_by_phone();
                break;
            case 5:
                find_phone_by_name();
                break;
            case 6:
                find_name_by_phone();
                break;
            case 7:
                cet_statistics();
                break;
            }
        }
    }