Writing my own object to a binary file.

[8Observer8]

Hi,

I want to write my own object to the binary file. But I receive the message:

C:\Qt\Qt5.1.1\5.1.1\mingw48_32\include\QtCore\qdat astream.h:300: error: no match for 'operator<<' (operand types are 'QDataStream' and 'const User')
s << *it;
^

void Dialog::on_btnWrite_clicked()
{
    QString nike = ui->wleNike->text();
    QString password = ui->wlePassword->text();
    QString firstName = ui->wleFirstName->text();
    QString lastName = ui->wleLastName->text();
    int age = ui->wspAge->text().toInt();
 
    User user;
    user.nike = nike;
    user.password = password;
    user.firstName = firstName;
    user.lastName = lastName;
    user.age = age;
 
    QVector<User> users;
    users.push_back(user);
 
    QString fileName = "c:/users.txt";
    QFile file(fileName);
 
    QDataStream out(&file);
    out.setVersion(QDataStream::Qt_5_1);
 
    out << users;
 
    file.flush();
    file.close();
}

void Dialog::on_btnWrite_clicked()
{
    QString nike = ui->wleNike->text();
    QString password = ui->wlePassword->text();
    QString firstName = ui->wleFirstName->text();
    QString lastName = ui->wleLastName->text();
    int age = ui->wspAge->text().toInt();

    User user;
    user.nike = nike;
    user.password = password;
    user.firstName = firstName;
    user.lastName = lastName;
    user.age = age;

    QVector<User> users;
    users.push_back(user);

    QString fileName = "c:/users.txt";
    QFile file(fileName);

    QDataStream out(&file);
    out.setVersion(QDataStream::Qt_5_1);

    out << users;

    file.flush();
    file.close();
}

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Thank you!

[ChrisW67]

You need to provide the operator<<() and operator>>() implementation for your User class. Its prototype looks like:

QDataStream &operator<<(QDataStream &, const User &);
QDataStream &operator>>(QDataStream &, User &);

QDataStream &operator<<(QDataStream &, const User &);
QDataStream &operator>>(QDataStream &, User &);

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Each should do whatever is necessary to save/restore the internal state of the User object.