I have a large array of floats and need to write sections of the array out to multiple files. The following code demonstrates an approach (that didn't work):

Qt Code: 
  1. const int FILES = 8;
  2.     QVector<QDataStream> v;
  3.  
  4.     for (int i=0; i<FILES; i++)
  5.     {
  6.         QString qstr("f");
  7.         qstr.append(QString::number(i));
  8.         qstr.append(".dat");
  9.         QFile f(qstr);
  10.         f.open(QIODevice::WriteOnly | QIODevice::Append);
  11.         QDataStream ds(&f);
  12.         v.append(ds);
  13.     }
  14.  
  15.     for (int cnt=0; cnt<99; cnt++)
  16.     {
  17.         for (int i=0; i<FILES; i++)
  18.         {
  19.             QDataStream ds = v.at(i);
  20.             ds << 999.9; // test
  21.         }
  22.     }
  23.     for (int i=0; i<FILES; i++)
  24.     {
  25.         v.at(i).device().close();
  26.     }
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This code gives the following compiler error:

QDataStream::QDataStream(const QDataStream&) is private

So, my solution was to replace the QVector<QDataStream> with pointers to QDataStream:


Qt Code: 
  1. const int FILES = 8;
  2.     QVector<QDataStream *> v;
  3.  
  4.     for (int i=0; i<FILES; i++)
  5.     {
  6.         QString qstr("f");
  7.         qstr.append(QString::number(i));
  8.         qstr.append(".dat");
  9.         QFile f(qstr);
  10.         f.open(QIODevice::WriteOnly | QIODevice::Append);
  11.         QDataStream *ds = new QDataStream(&f);
  12.         v.append(ds);
  13.     }
  14.  
  15.     for (int cnt=0; cnt<99; cnt++)
  16.     {
  17.         for (int i=0; i<FILES; i++)
  18.         {
  19.             QDataStream *ds = v.at(i);
  20.             *ds << 999.9; // test
  21.         }
  22.     }
  23.     for (int i=0; i<FILES; i++)
  24.     {
  25.         v.at(i)->device()->close();
  26.     }
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This compiled, but when it ran, the debugger stopped in qglobal.h at a line having something to do with QFlags. This is the line where it seems to break in qglobal.h:

inline QFlags operator&(Enum f) const { QFlags g; g.i = i & f; return g; }


I avoided this altogether by opening a QFile - QDataStream and writing values, then closing the stream each time within a loop. This worked but seems terribly inefficient.

Can someone demonstrate how to open and write to multiple binary files using QDataStream's operators?