Question

程序创建二进制随机访问文件“student.dat”用6条记录填充文件然后关闭文件。然后打开文件读/写，然后格式化并显示6条记录。然后显示几条记录然后更新然后再次显示以验证更新“已接受”。然后文件关闭。当达到返回时，即生成访问冲突写入位置....调试器指向的错误位于一个名为xutility line 217的系统文件中。我不知道xutility的作用。我的问题是我在程序运行后如何导致此错误，并执行它应该执行的所有操作。

添加注释：仅在打开文件进行输入时才会出现此错误。即ios :: in

这是我的主要代码：

/*******************************************************************************
*   CIS-278                                                                    *
*                                                                              *
*   Program Name:       Student_Main_Driver.cpp                                        *
*                                                                              *
*   Author:             Don Register                                           *
*                                                                              *
*   Written:            March 2015                                             *
*                                                                              *
*   Purpose:            Demonstrate the use of random access files.            *
*                                                                              *
*   Modifications:                                                             *
*                                                                              *
*******************************************************************************/

#include <cstdlib>
#include <iostream>
#include <fstream>
#include <sstream>
#include "Student.h"

using namespace std;

void displayOutput( Student &);

int main(int argc, char *argv[])
{
    fstream studentFile;
    studentFile.open("student.dat", ios::out | ios::binary);

    Student student01(1100, "Washington", "George", "Mil", 40, 3.77);
    Student student02(1200, "Jefferson ", "Thomas", "Gov", 45, 3.88);
    Student student03(1300, "Adams     ", "John  ", "Psy", 39, 3.79);
    Student student04(1400, "Franklin  ", "Ben   ", "Sci", 50, 3.89);
    Student student05(1500, "Hamilton  ", "Alex  ", "Pol", 42, 3.85);
    Student student06(1600, "Hancock   ", "John  ", "Pub", 48, 3.81);

    studentFile.write(reinterpret_cast<char*>(&student01),sizeof(Student));
    studentFile.write(reinterpret_cast<char*>(&student02),sizeof(Student));
    studentFile.write(reinterpret_cast<char*>(&student03),sizeof(Student));
    studentFile.write(reinterpret_cast<char*>(&student04),sizeof(Student));
    studentFile.write(reinterpret_cast<char*>(&student05),sizeof(Student));
    studentFile.write(reinterpret_cast<char*>(&student06),sizeof(Student));

    studentFile.close();

    studentFile.open("student.dat", ios::in | ios::out | ios::binary);

    Student studentNew;

    studentFile.read(reinterpret_cast<char*>(&studentNew), sizeof(Student));
    displayOutput(studentNew);

    studentFile.read(reinterpret_cast<char*>(&studentNew), sizeof(Student));
    displayOutput(studentNew);

    studentFile.read(reinterpret_cast<char*>(&studentNew), sizeof(Student));
    displayOutput(studentNew);

    studentFile.read(reinterpret_cast<char*>(&studentNew), sizeof(Student));
    displayOutput(studentNew);

    studentFile.read(reinterpret_cast<char*>(&studentNew), sizeof(Student));
    displayOutput(studentNew);

    studentFile.read(reinterpret_cast<char*>(&studentNew), sizeof(Student));
    displayOutput(studentNew);

    studentFile.seekg(1 * sizeof(Student), ios::beg);
    studentFile.read(reinterpret_cast<char*>(&studentNew), sizeof(Student));
    displayOutput(studentNew);

    studentFile.seekg(2 * sizeof(Student), ios::beg);
    studentFile.read(reinterpret_cast<char*>(&studentNew), sizeof(Student));
    displayOutput(studentNew);
    studentNew.setStudentMajorCode("CIS");
    studentFile.seekp(2 * sizeof(Student), ios::beg);
    studentFile.write(reinterpret_cast<char*>(&studentNew), sizeof(Student));
    studentFile.seekg(2 * sizeof(Student), ios::beg);
    studentFile.read(reinterpret_cast<char*>(&studentNew), sizeof(Student));
    displayOutput(studentNew);

    studentFile.seekg(3 * sizeof(Student), ios::beg);
    studentFile.read(reinterpret_cast<char*>(&studentNew), sizeof(Student));
    displayOutput(studentNew);
    studentNew.setStudentCreditsEarned(55);
    studentFile.seekp(3 * sizeof(Student), ios::beg);
    studentFile.write(reinterpret_cast<char*>(&studentNew), sizeof(Student));
    studentFile.seekg(3 * sizeof(Student), ios::beg);
    studentFile.read(reinterpret_cast<char*>(&studentNew), sizeof(Student));
    displayOutput(studentNew);

    studentFile.seekg(4 * sizeof(Student), ios::beg);
    studentFile.read(reinterpret_cast<char*>(&studentNew), sizeof(Student));
    displayOutput(studentNew);
    studentNew.setStudentGPA(3.91);
    studentFile.seekp(4 * sizeof(Student), ios::beg);
    studentFile.write(reinterpret_cast<char*>(&studentNew), sizeof(Student));
    studentFile.seekg(4 * sizeof(Student), ios::beg);
    studentFile.read(reinterpret_cast<char*>(&studentNew), sizeof(Student));
    displayOutput(studentNew);

    studentFile.close();

    cout << "\n\nPress Enter to continue. . .";
    char ch = getchar();

    return EXIT_SUCCESS; // this is where the error is generated

}  // end of main

void displayOutput(Student &studentNew)
{
    string outPut;
    outPut = studentNew.toString();
    cout << outPut;
}

这是我的student.h档案

// Student.h


#ifndef STUDENT_H
#define STUDENT_H

#include <cstdlib>
#include <string>
#include <sstream>

using namespace std;

class Student 
{
public:
    Student();  // default constructor
    Student(int, string, string, string, int, double);  // constructor with parameters
    ~Student(); // destructor

    // Setter methods
    void setStudentID(int);
    void setStudentLName(string);
    void setStudentFName(string);
    void setStudentMajorCode(string);
    void setStudentCreditsEarned(int);
    void setStudentGPA(double);

    // Getter methods
    int getStudentID();
    string getStudentLName();
    string getStudentFName();
    string getStudentMajorCode();
    int getStudentCreditsEarned();
    double getStudentGPA();

    string toString();

private:
    int studentID;
    string studentLName;
    string studentFName;
    string studentMajorCode;
    int studentCreditsEarned;
    double studentGPA;

};

#endif

Answer 1

static_assert( std::is_pod<Student>::value, "reading/writing as bytes is only safe and valid if you are a pod type" );

如果将其插入代码中，

可能会失败。

产生的错误将解释你做错了什么。

序列化非pod类型需要做的不仅仅是重新解释转换。您通常可以通过这种方式对pod类型进行分类（假设结构大小保持不变）。非托管类型（如std::string）需要自定义序列化/反序列化代码。

c ++抛出0xC0000005：访问冲突写入位置0xFEEEFEEE。从主要回来

1 个答案: