要求用C语言编写:1.先编写一个带结构的文件，存入电脑，要求第一行从左到右的内容依次是：姓名、名字、班级、学号，每排每列对齐，没有对齐的地方用空格补齐。2.从电脑中能够读入这个带结构的文件，并进行删增改后，重新存入电脑，3.这个文件要有纵横结构，每横表示一个记录4. 编出来的代码要能够在c的运行界面进行后续的插入、删除和修改

以下是一个简单的实现，其中学生信息存储在students.dat文件中，每个学生信息占据一行，每个字段用空格分隔，每个字段的最大宽度为MAX_NAME_LEN，例如姓名和名字的最大宽度为10个字符。代码中实现了插入、删除和修改学生信息的功能。

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

#define MAX_NAME_LEN 10
#define MAX_CLASS_LEN 10
#define MAX_ID_LEN 10
#define MAX_LINE_LEN (MAX_NAME_LEN*2+MAX_CLASS_LEN+MAX_ID_LEN+3)

struct student {
    char name[MAX_NAME_LEN];
    char surname[MAX_NAME_LEN];
    char class[MAX_CLASS_LEN];
    char id[MAX_ID_LEN];
};

void print_student(struct student *s) {
    printf("%-*s %-*s %-*s %s\n",
           MAX_NAME_LEN, s->name,
           MAX_NAME_LEN, s->surname,
           MAX_CLASS_LEN, s->class,
           s->id);
}

void print_header() {
    printf("%-*s %-*s %-*s %s\n",
           MAX_NAME_LEN, "姓名",
           MAX_NAME_LEN, "名字",
           MAX_CLASS_LEN, "班级",
           "学号");
    printf("%s\n", "===================================================");
}

void insert_student() {
    char line[MAX_LINE_LEN];
    struct student s;
    printf("请输入学生信息（姓名 名字 班级 学号）：");
    fgets(line, sizeof(line), stdin);
    sscanf(line, "%s %s %s %s", s.name, s.surname, s.class, s.id);
    FILE *fp = fopen("students.dat", "a");
    fprintf(fp, "%-*s %-*s %-*s %s\n",
            MAX_NAME_LEN, s.name,
            MAX_NAME_LEN, s.surname,
            MAX_CLASS_LEN, s.class,
            s.id);
    fclose(fp);
}

void delete_student() {
    char id[MAX_ID_LEN];
    printf("请输入要删除的学生学号：");
    scanf("%s", id);
    getchar();  // 把换行符读掉
    FILE *fp = fopen("students.dat", "r");
    FILE *fp_tmp = fopen("students.tmp", "w");
    char line[MAX_LINE_LEN];
    int deleted = 0;
    while (fgets(line, sizeof(line), fp)) {
        char tmp_id[MAX_ID_LEN];
        sscanf(line+MAX_NAME_LEN*2+MAX_CLASS_LEN+3, "%s", tmp_id);
        if (strcmp(tmp_id, id) == 0) {
            deleted = 1;
            continue;
        }
        fputs(line, fp_tmp);
    }
    fclose(fp);
    fclose(fp_tmp);
    if (deleted) {
        remove("students.dat");
        rename("students.tmp", "students.dat");
        printf("删除成功！\n");
    } else {
        remove("students.tmp");
        printf("找不到该学生！\n");
    }
}

void modify_student() {
    char id[MAX_ID_LEN];
    printf("请输入要修改的学生学号：");
    scanf("%s", id);
    getchar();  // 把换行符读掉
    FILE *fp = fopen("students.dat", "r");
    FILE *fp_tmp = fopen("students.tmp", "w");
    char line[MAX_LINE_LEN];
    int modified = 0;
    while (fgets(line, sizeof(line), fp)) {
        char tmp_id[MAX_ID_LEN];
        sscanf(line+MAX_NAME_LEN*2+MAX_CLASS_LEN+3, "%s", tmp_id);
        if (strcmp(tmp_id, id) == 0) {
            modified = 1;
            struct student s;
            printf("请输入学生信息（姓名 名字 班级 学号）：");
            fgets(line, sizeof(line), stdin);
            sscanf(line, "%s %s %s %s", s.name, s.surname, s.class, s.id);
            fprintf(fp_tmp, "%-*s %-*s %-*s %s\n",
                    MAX_NAME_LEN, s.name,
                    MAX_NAME_LEN, s.surname,
                    MAX_CLASS_LEN, s.class,
                    s.id);
        } else {
            fputs(line, fp_tmp);
        }
    }
    fclose(fp);
    fclose(fp_tmp);
    if (modified) {
        remove("students.dat");
        rename("students.tmp", "students.dat");
        printf("修改成功！\n");
    } else {
        remove("students.tmp");
        printf("找不到该学生！\n");
    }
}

int main() {
    while (1) {
        print_header();
        FILE *fp = fopen("students.dat", "r");
        char line[MAX_LINE_LEN];
        while (fgets(line, sizeof(line), fp)) {
            struct student s;
            sscanf(line, "%s %s %s %s", s.name, s.surname, s.class, s.id);
            print_student(&s);
        }
        fclose(fp);
        printf("\n请选择操作：\n");
        printf("1. 插入学生信息\n");
        printf("2. 删除学生信息\n");
        printf("3. 修改学生信息\n");
        printf("4. 退出程序\n");
        int choice;
        scanf("%d", &choice);
        getchar();  // 把换行符读掉
        switch (choice) {
            case 1:
                insert_student();
                break;
            case 2:
                delete_student();
                break;
            case 3:
                modify_student();
                break;
            case 4:
                return 0;
            default:
                printf("无效的选项！\n");
                break;
        }
    }
    return 0;
}