如何使用C ++在向量中成功写入.DAT文件内容？

Question

我正在尝试将保存在名为PatientInSystem的向量中的已保存患者列表写入.DAT文件。 但是，由于某些原因，它将无法正常工作。 有人知道我可能做错了吗？

if (!PatientsInSystem.empty()) {
            cout << "Error. There are still patients checked in. They must be checked out before quitting." << endl;
            cout << "Printing remaining patients in the system... " << endl;
            for (int i = 0; i < PatientsInSystem.size(); i++) {
                cout << "Patient's ID: " << PatientsInSystem.at(i)->getID() << endl;
                cout << "Patient's Name: " << PatientsInSystem.at(i)->getFirstName() << " " << PatientsInSystem.at(i)->getLastName() << endl;
                cout << "Patient's Birthday: " << PatientsInSystem.at(i)->getBirthDate() << endl;
                cout << "Patient's Primary Doctor's ID: " << PatientsInSystem.at(i)->getPrimaryDoctorID() << endl;
            }
        }
        else {
            outFile.open("CurrentPatients.dat", ios::out | ios::binary);
            if (!outFile.is_open()) {
                cout << "File not open." << endl;
            }
            else {
                cout << "Binary file open, saving patients now...\n";
                cout << "----------------------------------------\n";
                for (int i = 0; i < PatientsInSystem.size(); i++) {
                    Patient * p;
                    p = PatientsInSystem.at(i);
                    outFile.write(reinterpret_cast<char *> (&p), sizeof(p));
                }
            }

            outFile.close();

[下一部分代码与上述相同，仅在获得第一笔帮助后才进行编辑]

这是代码的编辑版本... PatientList是我的临时载体，必须清空以使PatientInSystem矢量写入文件

case 'q': {

        if (!PatientList.empty()) {
            cout << "Error. There are still patients checked in. They must be checked out before quitting." << endl;
            cout << "Printing remaining patients in the system... " << endl;
            for (int i = 0; i < PatientList.size(); i++) {
                cout << "Patient's ID: " << PatientList.at(i)->getID() << endl;
                cout << "Patient's Name: " << PatientList.at(i)->getFirstName() << " " << PatientList.at(i)->getLastName() << endl;
                cout << "Patient's Birthday: " << PatientList.at(i)->getBirthDate() << endl;
                cout << "Patient's Primary Doctor's ID: " << PatientList.at(i)->getPrimaryDoctorID() << endl;
            }
        }
        else {
            outFile.open("CurrentPatients.dat", ios::out | ios::binary);
            if (!outFile.is_open()) {
                cout << "File not open." << endl;
            }
            else {
                cout << "Binary file open, saving patients now...\n";
                cout << "----------------------------------------\n";
                for (int i = 0; i < PatientsInSystem.size(); i++) {
                    outFile.write(reinterpret_cast<char *> (PatientsInSystem.at(i)), sizeof(Patient));
                }
            }

            outFile.close();

Answer 1

您是否有理由使用指针数组与平面数组？

您正在编写局部指针变量p ，而不是Patient数据。 您只需传递p而不是&p （或直接传递.at（）），并且bytes参数应该是sizeof(Patient) 。

如果这些是指向不同大小的派生类的指针，则会出现问题。

另外，不会每次都输入循环，因为当.empty()为true时，在所输入的块中输入了该循环。