用c语言写一个学生学籍管理系统 主要功能: 欢迎及菜单页面 通过文本文件读入学生信息 新增学生(学号不可重复) 录入成绩 删除学生 展示所有学生信息 计算最高最低平均成绩 统计ABCD每个分段的人数 按成绩从高到低排序 按学号排序 退出前将所有学生信息回写进文本文档

很好，以下是一个简单的学生学籍管理系统的C语言实现：

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

#define MAX_STUDENTS 100

struct student {
    char id[20];
    char name[20];
    int score;
};

int num_students = 0;
struct student students[MAX_STUDENTS];

void load_students(char *filename) {
    FILE *fp = fopen(filename, "r");
    if (!fp) {
        printf("Error: cannot open file %s for reading\n", filename);
        return;
    }
    char line[100];
    while (fgets(line, sizeof(line), fp)) {
        char *p = strtok(line, ",");
        strcpy(students[num_students].id, p);
        p = strtok(NULL, ",");
        strcpy(students[num_students].name, p);
        p = strtok(NULL, ",");
        students[num_students].score = atoi(p);
        num_students++;
    }
    fclose(fp);
}

void save_students(char *filename) {
    FILE *fp = fopen(filename, "w");
    if (!fp) {
        printf("Error: cannot open file %s for writing\n", filename);
        return;
    }
    for (int i = 0; i < num_students; i++) {
        fprintf(fp, "%s,%s,%d\n", students[i].id, students[i].name, students[i].score);
    }
    fclose(fp);
}

struct student *find_student(char *id) {
    for (int i = 0; i < num_students; i++) {
        if (strcmp(students[i].id, id) == 0) {
            return &students[i];
        }
    }
    return NULL;
}

void add_student() {
    struct student s;
    printf("Enter student ID: ");
    scanf("%s", s.id);
    if (find_student(s.id)) {
        printf("Error: student with ID %s already exists\n", s.id);
        return;
    }
    printf("Enter student name: ");
    scanf("%s", s.name);
    printf("Enter student score: ");
    scanf("%d", &s.score);
    students[num_students++] = s;
    printf("Student added successfully\n");
}

void remove_student() {
    char id[20];
    printf("Enter student ID: ");
    scanf("%s", id);
    struct student *s = find_student(id);
    if (!s) {
        printf("Error: student with ID %s does not exist\n", id);
        return;
    }
    for (int i = 0; i < num_students; i++) {
        if (&students[i] == s) {
            for (int j = i; j < num_students - 1; j++) {
                students[j] = students[j + 1];
            }
            num_students--;
            printf("Student removed successfully\n");
            return;
        }
    }
}

void display_all_students() {
    printf("ID\tName\tScore\n");
    for (int i = 0; i < num_students; i++) {
        printf("%s\t%s\t%d\n", students[i].id, students[i].name, students[i].score);
    }
}

void compute_statistics() {
    int min_score = students[0].score;
    int max_score = students[0].score;
    int sum_score = 0;
    int count_a = 0, count_b = 0, count_c = 0, count_d = 0;
    for (int i = 0; i < num_students; i++) {
        int score = students[i].score;
        if (score < min_score) {
            min_score = score;
        }
        if (score > max_score) {
            max_score = score;
        }
        sum_score += score;
        if (score >= 90) {
            count_a++;
        } else if (score >= 80) {
            count_b++;
        } else if (score >= 70) {
            count_c++;
        } else {
            count_d++;
        }
    }
    double avg_score = (double) sum_score / num_students;
    printf("Minimum score: %d\n", min_score);
    printf("Maximum score: %d\n", max_score);
    printf("Average score: %.2f\n", avg_score);
    printf("A: %d\n", count_a);
    printf("B: %d\n", count_b);
    printf("C: %d\n", count_c);
    printf("D: %d\n", count_d);
}

void sort_by_score() {
    for (int i = 0; i < num_students - 1; i++) {
        for (int j = i + 1; j < num_students; j++) {
            if (students[i].score < students[j].score) {
                struct student tmp = students[i];
                students[i] = students[j];
                students[j] = tmp;
            }
        }
    }
    printf("Students sorted by score\n");
}

void sort_by_id() {
    for (int i = 0; i < num_students - 1; i++) {
        for (int j = i + 1; j < num_students; j++) {
            if (strcmp(students[i].id, students[j].id) > 0) {
                struct student tmp = students[i];
                students[i] = students[j];
                students[j] = tmp;
            }
        }
    }
    printf("Students sorted by ID\n");
}

int main() {
    char filename[] = "students.txt";
    load_students(filename);
    printf("Welcome to Student Management System!\n");
    while (1) {
        printf("\nMenu:\n");
        printf("1. Add student\n");
        printf("2. Remove student\n");
        printf("3. Display all students\n");
        printf("4. Compute statistics\n");
        printf("5. Sort by score\n");
        printf("6. Sort by ID\n");
        printf("7. Save & quit\n");
        int choice;
        printf("Enter your choice: ");
        scanf("%d", &choice);
        switch (choice) {
            case 1:
                add_student();
                break;
            case 2:
                remove_student();
                break;
            case 3:
                display_all_students();
                break;
            case 4:
                compute_statistics();
                break;
            case 5:
                sort_by_score();
                break;
            case 6:
                sort_by_id();
                break;
            case 7:
                save_students(filename);
                printf("Goodbye!\n");
                return 0;
            default:
                printf("Invalid choice, please try again\n");
        }
    }
}

注意，这只是一个简单的示例，实际应用中可能需要更多的功能和更复杂的逻辑。