Help with Qt Invalid conversion

houmingc

Error created in below code
a-invalid conversion from 'unsigned char' to 'const char*'
b-no matching function for call to 'QSerialPort::write(QString)

@
void MainWindow::SendContrast()
{

        static const char Contrast0[]={0x08,0x11,0x01,0x00,0x00,'\0'};
        static const char Contrast1[]={0x04,0x12,0x84,'\0'};

        serial->write(Contrast0);
        serial->write(ui->ContrastCombo->currentText());      //a
        serial->write(ModBusCRC(Contrast0,sizeof(Contrast0)));    //b because ModBusCRC return a const char
        serial->write(Contrast1);
        serial->write(ModBusCRC(Contrast1,sizeof(Contrast1)));

}

@

SGaist

Hi,

currentText() returns a QString where write wants a QByteArray so you have to convert it using e.g. toLatin1().

Where exactly does the other error happen ?

houmingc

thanks, i edit the question.
Understood QLatin1 better now
http://qt-project.org/doc/qt-4.8/qlatin1string.html

SGaist

Then something like:

@
char crc = ModBusCRC(Contrast0,sizeof(Contrast0));
serial->write(&crc, 1);
@

should work.