how to copy a QString value to a struct

[aha_1980]

@ManiRon How does your QString look like?

[ManiRon]

@aha_1980 its a variable in which i will store the values read from the data transmitted from server side

[aha_1980]

@ManiRon Yeah, but what are it's contents? Is it printable? Then how does it look?

[ManiRon]

@aha_1980

it is contains a normal data which can be printed like for example(1,2,3) like these values it has

[aha_1980]

@ManiRon If you cannot give us a concrete full example then we cannot give you a concrete answer. Sorry

[ManiRon]

@aha_1980

i am not understanding and how to explain it . its a simple QString variable and i store the read data in that variable and i want to copy that values to the struct which i have mentioned above .

[ManiRon]

This post is deleted!

[ManiRon]

@aha_1980

 QDataStream in(tcpSocket);
    //in.setVersion(QDataStream::Qt_5_10);
    for (;;)
    {
        if (!m_nNextBlockSize)
        {
            if (tcpSocket->bytesAvailable() < sizeof(quint16)) { break; }
            in >> m_nNextBlockSize;
        }

        if (tcpSocket->bytesAvailable() < m_nNextBlockSize) { break; }

        QString str; in >> str;
        
        

        if (str == "0")
        {
            str = "Connection closed";
            closeConnection();
        }

        emit hasReadSome(str);
        m_nNextBlockSize = 0;
    }
} 

and i want to copy the QString str contained values to the struct given above

[jsulm]

@ManiRon said in how to copy a QString value to a struct:

i am not understanding and how to explain it

Can't you simply show an example of such a string?
Also, why do you convert the byte array to a string first?
The way it usually works is: implement << and >> operators for your structure (for QDataStream, https://doc.qt.io/qt-5/qdatastream.html). Then you can simply do it like:

TxCommandPacket packet;
in >> packet;

[J.Hilk]

@ManiRon this only works, because QString haccepts a QByteArray as a Constructor/DataStream overload.

Are you really sure you want to save the data in a QString and not in a QByteArray ?
a QString will terminate if the QByteArray contains char it can not represent.

That said, there are multiple ways to skin this cat.

• give your struct a QDataStream operator laid @jsulm said.

• copy the raw data form the string or QbyteArray into the allocated char array

struct Foo{
    int a;
    int b;
    char data [500];
};

    QString s ("Hello World");
    Foo bar;

    memcpy(&bar.data, s.data(),s.size()*2);

• or if you wan't to go really old school:

    QString s ("Hello World");
    Foo bar;

    memcpy(reinterpret_cast<char*>(&bar) + sizeof(int)*2, s.data(),s.size()*2);

just the 3 way's I'm thinking of right now.

[aha_1980]

@J.Hilk you are aware that QChar is 16 bit, so QString::size() is only half the memory it uses...

Anyway, the OP don't want QString, rather QByteArray.

[J.Hilk]

@aha_1980 said in how to copy a QString value to a struct:

@J.Hilk you are aware that QChar is 16 bit, so QString::size() is only half the memory it uses...

thanks for clarifying that I was looking through the documentation, scratching my head, why my example project only copied "Hello " back!

I'll fix my post!

[ManiRon]

This post is deleted!