用c语言写:设计和实现一个简单的学生管理系统,具有以下功能:1.学生信息录入:可以录入学生的基本信息,包括学号、姓名、性别、年龄、所在院系等信息。要求支持多名学生信息的录入。2.学生信息查询:可以按学号或姓名进行学生信息的查询,找到相应学生的基本信息。3.学生成绩录入:可以为每名学生录入多门课程的成绩,包括课程名称、学分、成绩等。4.学生成绩查询:可以按学号和课程名称查询某名学生的指定课程成绩。5.课程平均分查询:可以查询每门课程的平均成绩。6.学生总分统计:可以统计每名学生的总学分和总成绩,以及根据总成绩计算学生的平均分。该系统需要提供一个菜单界面,让用户选择不同的功能;需要定义学生信息结构体和成绩结构体、考虑利用数据文件等存储数据。

好的，以下是一个简单的学生管理系统的C语言代码：

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

#define MAX_STUDENT 100
#define MAX_COURSE 10

struct course {
    char name[20];
    int credit;
    float score;
};

struct student {
    char id[10];
    char name[20];
    char sex[5];
    int age;
    char department[20];
    struct course courses[MAX_COURSE];
    int course_count;
};

struct student students[MAX_STUDENT];
int student_count = 0;

void add_student() {
    if (student_count >= MAX_STUDENT) {
        printf("Error: Maximum number of students reached!\n");
        return;
    }

    struct student s;
    printf("Enter student information:\n");
    printf("ID: ");
    scanf("%s", s.id);
    printf("Name: ");
    scanf("%s", s.name);
    printf("Sex: ");
    scanf("%s", s.sex);
    printf("Age: ");
    scanf("%d", &s.age);
    printf("Department: ");
    scanf("%s", s.department);

    s.course_count = 0;

    students[student_count++] = s;
    printf("Student added successfully!\n");
}

void add_score() {
    char id[10];
    printf("Enter the student ID: ");
    scanf("%s", id);

    struct student *s = NULL;
    for (int i = 0; i < student_count; i++) {
        if (strcmp(students[i].id, id) == 0) {
            s = &students[i];
            break;
        }
    }

    if (s == NULL) {
        printf("Error: Student not found!\n");
        return;
    }

    char name[20];
    printf("Enter the course name: ");
    scanf("%s", name);

    for (int i = 0; i < s->course_count; i++) {
        if (strcmp(s->courses[i].name, name) == 0) {
            printf("Error: Course already exists!\n");
            return;
        }
    }

    if (s->course_count >= MAX_COURSE) {
        printf("Error: Maximum number of courses reached!\n");
        return;
    }

    struct course c;
    strcpy(c.name, name);
    printf("Enter the course credit: ");
    scanf("%d", &c.credit);
    printf("Enter the course score: ");
    scanf("%f", &c.score);

    s->courses[s->course_count++] = c;
    printf("Score added successfully!\n");
}

void query_student() {
    char id[10];
    printf("Enter the student ID or name: ");
    scanf("%s", id);

    int found = 0;
    for (int i = 0; i < student_count; i++) {
        if (strcmp(students[i].id, id) == 0 || strcmp(students[i].name, id) == 0) {
            printf("ID: %s\n", students[i].id);
            printf("Name: %s\n", students[i].name);
            printf("Sex: %s\n", students[i].sex);
            printf("Age: %d\n", students[i].age);
            printf("Department: %s\n", students[i].department);

            printf("Courses:\n");
            for (int j = 0; j < students[i].course_count; j++) {
                printf("%s: %d credits, score %.1f\n", students[i].courses[j].name, students[i].courses[j].credit, students[i].courses[j].score);
            }

            found = 1;
            break;
        }
    }

    if (!found) {
        printf("Error: Student not found!\n");
    }
}

void query_score() {
    char id[10];
    printf("Enter the student ID: ");
    scanf("%s", id);

    struct student *s = NULL;
    for (int i = 0; i < student_count; i++) {
        if (strcmp(students[i].id, id) == 0) {
            s = &students[i];
            break;
        }
    }

    if (s == NULL) {
        printf("Error: Student not found!\n");
        return;
    }

    char name[20];
    printf("Enter the course name: ");
    scanf("%s", name);

    int found = 0;
    for (int i = 0; i < s->course_count; i++) {
        if (strcmp(s->courses[i].name, name) == 0) {
            printf("%s: %d credits, score %.1f\n", s->courses[i].name, s->courses[i].credit, s->courses[i].score);
            found = 1;
            break;
        }
    }

    if (!found) {
        printf("Error: Course not found!\n");
    }
}

void query_course() {
    char name[20];
    printf("Enter the course name: ");
    scanf("%s", name);

    int count = 0;
    float sum = 0.0;
    for (int i = 0; i < student_count; i++) {
        for (int j = 0; j < students[i].course_count; j++) {
            if (strcmp(students[i].courses[j].name, name) == 0) {
                count++;
                sum += students[i].courses[j].score;
            }
        }
    }

    if (count == 0) {
        printf("Error: Course not found!\n");
        return;
    }

    printf("Average score for course %s is %.1f\n", name, sum / count);
}

void query_summary() {
    printf("Student summary:\n");
    for (int i = 0; i < student_count; i++) {
        float sum = 0.0;
        int credits = 0;
        for (int j = 0; j < students[i].course_count; j++) {
            sum += students[i].courses[j].score * students[i].courses[j].credit;
            credits += students[i].courses[j].credit;
        }

        printf("%s: %d credits, total score %.1f, average score %.1f\n", students[i].name, credits, sum, sum / credits);
    }
}

void menu() {
    printf("\nStudent Management System\n");
    printf("=========================\n");
    printf("1. Add student\n");
    printf("2. Add score\n");
    printf("3. Query student\n");
    printf("4. Query score\n");
    printf("5. Query course average score\n");
    printf("6. Query student summary\n");
    printf("0. Exit\n");
    printf("Please enter your choice: ");
}

int main() {
    int choice = 0;
    while (1) {
        menu();
        scanf("%d", &choice);

        switch (choice) {
            case 1:
                add_student();
                break;
            case 2:
                add_score();
                break;
            case 3:
                query_student();
                break;
            case 4:
                query_score();
                break;
            case 5:
                query_course();
                break;
            case 6:
                query_summary();
                break;
            case 0:
                printf("Goodbye!\n");
                exit(0);
            default:
                printf("Error: Invalid choice!\n");
                break;
        }
    }

    return 0;
}

注意，这只是一个简单的实现，没有考虑输入的安全性和健壮性，如果需要更加完善的操作，还需要进一步优化。