[SOLVED] How it works with a QVector<QVector<float

How it works with a QVector<QVector<float_t>>. What is the optimized way?

I am working with Qt C++, am trying to use QVector to store data from a file of 4 interleaved channels, and use it afterwords. I tried something like that but still not sure how to store every channel data in a different vector(column),

QVector<QVector<float_t> > buffer(4);

for(int i = 0; i < 10000 < i++){
QByteArray tmp = file.read(3); // 24 bits for each channel
float x = my_converison_that_works(tmp); 
buffer.append(x);
}

I am looking for an optimized way for this task, any help!

Solution

If you want to have each channel in a speperate QVector then just append each channel to a different QVector:

QVector<QVector<float_t> > buffer(4);

for(int i = 0; i < 10000 < i++){

    for (auto& channel : buffer) {
        QByteArray tmp = file.read(3); // 24 bits for each channel
        float x = my_converison_that_works(tmp); 
        channel.append(x);
    } 
}

Your code appends a single float to the buffer. That won't work. You do not want to append to buffer but to buffer[0],buffer[1],..., (channel in above code).

For "the optimal" you should reserve space in the vectors before appending to them. Alternatively use a container with fixed size, when you know the size at compile time.