C语言编程，设计编写一个传统的小型学生信息管理系统，需要完整代码。 1、该系统可以用于管理一个班的学生信息。学生人数在50人左右。 2、该系统存放了有关学生的某些方面的信息：如学号、姓名、性别、出生日期、成绩、所在系等，具体包含的数据内容由设计者分析确定。 3、所有学生信息的数据结构及其存储结构由设计者分析确定。 4、所有学生的信息数据可以用文件形式存放。（可选项） 5、该系统具有相关的数据输入、输出、查询、修改、插入、删除、统计、排序等功能。（功能的多少设计者可根据需要自行调整，但必须具备输出、输出、查询、某一方面数据统计的基本功能。） 6、系统应具有友好的用户界面，并能够让用户通过菜单进行相应功能的选择。 7、选用适当的算法和数据结构，建立相应的程序代码。

以下是一个简单的学生信息管理系统的C语言代码，实现基本的增删改查和文件存储功能，具体细节可以根据实际需求进行修改和完善：

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

#define MAX_STU_NUM 50
#define FILE_NAME "student.dat"

typedef struct {
    char id[20];
    char name[20];
    char gender[5];
    char birth[20];
    int score;
    char department[20];
} Student;

Student stuList[MAX_STU_NUM];
int stuNum = 0;

void printMenu() {
    printf("1. Add a student\n");
    printf("2. Delete a student\n");
    printf("3. Modify student information\n");
    printf("4. Query student information\n");
    printf("5. Display all students\n");
    printf("6. Save to file\n");
    printf("7. Load from file\n");
    printf("8. Exit\n");
}

void addStudent() {
    if (stuNum >= MAX_STU_NUM) {
        printf("The student list is full!\n");
        return;
    }
    Student newStu;
    printf("Please input the student ID: ");
    scanf("%s", newStu.id);
    printf("Please input the student name: ");
    scanf("%s", newStu.name);
    printf("Please input the student gender: ");
    scanf("%s", newStu.gender);
    printf("Please input the student birth: ");
    scanf("%s", newStu.birth);
    printf("Please input the student score: ");
    scanf("%d", &newStu.score);
    printf("Please input the student department: ");
    scanf("%s", newStu.department);
    stuList[stuNum++] = newStu;
    printf("Add student successfully!\n");
}

void deleteStudent() {
    char id[20];
    printf("Please input the ID of the student you want to delete: ");
    scanf("%s", id);
    int index = -1;
    for (int i = 0; i < stuNum; i++) {
        if (strcmp(stuList[i].id, id) == 0) {
            index = i;
            break;
        }
    }
    if (index == -1) {
        printf("The student is not found!\n");
        return;
    }
    for (int i = index; i < stuNum - 1; i++) {
        stuList[i] = stuList[i + 1];
    }
    stuNum--;
    printf("Delete student successfully!\n");
}

void modifyStudent() {
    char id[20];
    printf("Please input the ID of the student you want to modify: ");
    scanf("%s", id);
    int index = -1;
    for (int i = 0; i < stuNum; i++) {
        if (strcmp(stuList[i].id, id) == 0) {
            index = i;
            break;
        }
    }
    if (index == -1) {
        printf("The student is not found!\n");
        return;
    }
    Student newStu;
    printf("Please input the new student ID (or press Enter to skip): ");
    fgets(newStu.id, 20, stdin);
    if (newStu.id[0] != '\n') {
        newStu.id[strcspn(newStu.id, "\n")] = 0;
    }
    printf("Please input the new student name (or press Enter to skip): ");
    fgets(newStu.name, 20, stdin);
    if (newStu.name[0] != '\n') {
        newStu.name[strcspn(newStu.name, "\n")] = 0;
    }
    printf("Please input the new student gender (or press Enter to skip): ");
    fgets(newStu.gender, 5, stdin);
    if (newStu.gender[0] != '\n') {
        newStu.gender[strcspn(newStu.gender, "\n")] = 0;
    }
    printf("Please input the new student birth (or press Enter to skip): ");
    fgets(newStu.birth, 20, stdin);
    if (newStu.birth[0] != '\n') {
        newStu.birth[strcspn(newStu.birth, "\n")] = 0;
    }
    printf("Please input the new student score (or press Enter to skip): ");
    char buf[10];
    fgets(buf, 10, stdin);
    if (buf[0] != '\n') {
        newStu.score = atoi(buf);
    } else {
        newStu.score = stuList[index].score;
    }
    printf("Please input the new student department (or press Enter to skip): ");
    fgets(newStu.department, 20, stdin);
    if (newStu.department[0] != '\n') {
        newStu.department[strcspn(newStu.department, "\n")] = 0;
    }
    stuList[index] = newStu;
    printf("Modify student information successfully!\n");
}

void queryStudent() {
    char id[20];
    printf("Please input the ID of the student you want to query: ");
    scanf("%s", id);
    int index = -1;
    for (int i = 0; i < stuNum; i++) {
        if (strcmp(stuList[i].id, id) == 0) {
            index = i;
            break;
        }
    }
    if (index == -1) {
        printf("The student is not found!\n");
        return;
    }
    printf("ID: %s\n", stuList[index].id);
    printf("Name: %s\n", stuList[index].name);
    printf("Gender: %s\n", stuList[index].gender);
    printf("Birth: %s\n", stuList[index].birth);
    printf("Score: %d\n", stuList[index].score);
    printf("Department: %s\n", stuList[index].department);
}

void displayAll() {
    if (stuNum == 0) {
        printf("No student information is stored!\n");
        return;
    }
    printf("ID\tName\tGender\tBirth\tScore\tDepartment\n");
    for (int i = 0; i < stuNum; i++) {
        printf("%s\t%s\t%s\t%s\t%d\t%s\n", stuList[i].id, stuList[i].name, stuList[i].gender, stuList[i].birth, stuList[i].score, stuList[i].department);
    }
}

void saveToFile() {
    FILE *fp = fopen(FILE_NAME, "wb");
    if (fp == NULL) {
        printf("Failed to open file!\n");
        return;
    }
    fwrite(&stuNum, sizeof(int), 1, fp);
    fwrite(stuList, sizeof(Student), stuNum, fp);
    fclose(fp);
    printf("Save to file successfully!\n");
}

void loadFromFile() {
    FILE *fp = fopen(FILE_NAME, "rb");
    if (fp == NULL) {
        printf("Failed to open file!\n");
        return;
    }
    fread(&stuNum, sizeof(int), 1, fp);
    fread(stuList, sizeof(Student), stuNum, fp);
    fclose(fp);
    printf("Load from file successfully!\n");
}

int main() {
    int choice;
    while (1) {
        printMenu();
        printf("Please input your choice: ");
        scanf("%d", &choice);
        switch (choice) {
            case 1:
                addStudent();
                break;
            case 2:
                deleteStudent();
                break;
            case 3:
                modifyStudent();
                break;
            case 4:
                queryStudent();
                break;
            case 5:
                displayAll();
                break;
            case 6:
                saveToFile();
                break;
            case 7:
                loadFromFile();
                break;
            case 8:
                exit(0);
            default:
                printf("Invalid choice!\n");
                break;
        }
    }
    return 0;
}