Qt ActiveX data types

Question

I am developing a C++/Qt application that communicates with an ActiveX server. I try to use a function that returns a reference to an array of floats as a parameter. The function prototype is:

Frequencies([in, out] SAFEARRAY(float)*)

My code is:

QList<QVariant> variantList;
object->dynamicCall("Frequencies(QList<QVariant>&)", variantList);

But unfortunately I have the following error: Type Mismatch in Parameter. Pass an array of type string or real.

After reading this document I also tried QList<QString>& and QList<float>& with no success.

The documentation of the ActiveX server says: Use a safearray of strings (VT_BSTR) or reals (VT_R8 for double or VT_R4 for float).

Any idea?

Thanks!

Answer 1

The Qt example doesn't show how to read the results. It was my problem...

QList<QString> values;
for(int i=0; i<nbFrequencies; i++) {
    values << "0.0";
}
QList<QVariant> variantList;
parameters << QVariant(values);
object->dynamicCall("Frequencies(QList<QString>&)", variantList);

values = variantList.first().toStringList();

for(int j=0; j<values.size(); j++) {
    qDebug() << values.at(j);
}

It is necessary to read the first element of variantList and to convert it to a QStringList. Very simply...