Qt : How to debug a bad alloc exception in QByteArray?

Question

I have a QNetworkReply and I want to store the downloaded bytes in a QByteArray .

connect(_replyRef, SIGNAL(readyRead()), this, SLOT(PushDownloadedBytesToFile()));
void PushDownloadedBytesToFile()
{
     _internalBufferBytes.append(_replyRef->readAll());
}

The problem is that I get a bad alloc when the size is approximately 33552950.

I do not understand what is the problem or how can I debug this.

Answer 1

From you comment, regarding maintaining 40 MB in buffer, I'd suggest to reserve this much memory (more would be better) in advance using QByteArray::reserve() API. But, with QByteArray , you have to maintain the total size, consumed size, current index, etc.

Another solution could be to use QString with reserve() . You wouldn't have to maintain the details. You can simply use QString::append() and then convert it to QByteArray using QString::toUtf8() whenever you need it.