程序如下：

#include "stdafx.h"
#include <cstdio>
#include <cstdlib>
#include <conio.h>

struct Student
{
    char Name[11];
    char Sex;
    long Birthday;
    Student* next;
};

void Init(void);
void Save_Data(const char* filename, Student* students, size_t count);
Student* Load_Data(const char* filename);
void Update_Data(const char* filename, const Student* student, size_t index);
void List_Students(Student* students);
void Show_Student(const Student* student);
void free_shuju(Student* head);
const char* FileName = "Students.DAT";

int main(void)
{
    Init();

    Student* students = Load_Data(FileName);
    List_Students(students);

    printf_s("Now update record 2\n");
    students->next->Birthday = 19921014;
    students->next->Sex = 0;
    Update_Data(FileName, students->next, 2);    // 用指针students-next所指向的数据，刷写文件中的第2条记录
    students = Load_Data(FileName);
    List_Students(students);
    free_shuju(students);
    printf_s("\nPress any key to continue...");
    _getch();
    return EXIT_SUCCESS;
}

void Init(void)
{
    Student students[3] = {
        { "张三", 0, 19920312 },
        { "李四", 1, 19921004 },
        { "王五", 0, 19930120 }
    };
    Save_Data(FileName, students, _countof(students));
}

void Save_Data(const char* filename, Student* students, size_t count)
{
    FILE* file;

    if (fopen_s(&file, filename, "wb") == 0)
    {
        fwrite(&count, sizeof(count), 1, file);
        for (size_t index = 0; index < count; ++index)
        {
            fwrite(&students[index], sizeof(Student), 1, file);
        }
        fclose(file);
    }
    else
    {
        printf_s("File %s create failure.\n", filename);
    }
}

Student* Load_Data(const char* filename)
{
    FILE* file;
    Student* head = NULL;

    if (fopen_s(&file, filename, "rb") == 0)
    {
        size_t count;
        Student* previous = NULL;
        fread(&count, sizeof(count), 1, file);
        for (size_t index = 0; index < count; ++index)
        {
            Student* stu = (Student*)calloc(1, sizeof(Student));
            if (stu != NULL)
            {
                (previous != NULL) ? (previous->next = stu) : (head = stu);
                fread(stu, sizeof(Student), 1, file);
                previous = stu;
            }
            else
            {
                printf_s("Memory allocation error.\n");
                break;
            }
        }
        fclose(file);
    }
    else
    {
        printf_s("File %s read failure.\n", filename);
    }

    return head;
}

void Update_Data(const char* filename, const Student* student, size_t index)
{
    FILE* file;

    if (fopen_s(&file, filename, "rb+") == 0)
    {
        size_t count;
        fread(&count, sizeof(count), 1, file);
        fseek(file, (index - 1) * sizeof(Student), SEEK_CUR);
        fwrite(student, sizeof(Student), 1, file);
        fclose(file);
    }
    else
    {
        printf_s("File %s update failure.\n", filename);
    }
}

void List_Students(Student* students)
{
    while (students != NULL)
    {
        Show_Student(students);
        students = students->next;
    }
}

void Show_Student(const Student* student)
{
    printf_s("%-10s   %2s   %u\n", student->Name, (student->Sex == 0) ? "男" : "女", student->Birthday);
}

void free_shuju(Student* head)
{
   if(head!=NULL)
   {
      Student* sf;
      sf=head;
     do
     {
       free(sf);
       sf=sf->next;
     }while(sf!=NULL);
   }
}

调试之后出现这样的情况：

我建的文件是CPP啊，运行之后就自动跳出来个C文件出来。

可能是我编译器的问题，你给我的程序我去编译，会cstdio，cstdlib两个页面，然后一大堆错误在里面报错。
我用VS2010，建立C文件，建立的过程应该是对的。纳闷中。。。。。

[ 本帖最后由 列车永不停息 于 2015-8-8 20:47 编辑 ]