Qt: Write Struct to File

Question

I\'m struggling with writing a struct to a file via QFile in Qt.

typedef struct {
    uint32_t timestamp;
    uint32_t recordType;
             


        

Answer 1

Another thing is that to keep Qt compatibility rename some native types, so I recommend using equivalent types, in addition to using QString directly instead of char * payload and payloadLength as shown below:

struct DataPacket{
    quint32 timestamp;
    quint32 recordType;
    QString payload;
};

Also when writing it is better to use QDataStream as shown below:

QDataStream &operator>>(QDataStream &in, DataPacket &p){
    in >> p.timestamp >> p.recordType >>p.payload;
    return in;
}

QDataStream &operator<<(QDataStream &out, const DataPacket &p){
    out << p.timestamp << p.recordType <

The following example shows its use:

int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);

    const QString fileName = "file.log";

    QString dataString = "$GPGSA,M,3,03,23,22,19,17,01,09,31,12,,,,1.9,0.9,1.6*3D";

    DataPacket pin{1000, 123, dataString};

    QFile fout(fileName);
    if(fout.open(QIODevice::WriteOnly)){
        QDataStream out(&fout);
        out<>pout;
        qDebug()<

Output:

1000 123 "$GPGSA,M,3,03,23,22,19,17,01,09,31,12,,,,1.9,0.9,1.6*3D"

Note: QDataStream sets payloadLength indirectly because it knows the size of QString.