using Qlist with a class

[jacek]

How do I then use the .append() since it needs an argument, and my class does not take arguments?

QList< Something * > list;
 
Something * something = new Something();
list.append( something );
// or simply:
list.append( new Something() );

QList< Something * > list;

Something * something = new Something();
list.append( something );
// or simply:
list.append( new Something() );

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Don't forget to delete the items when you remove them from the list (qDeleteAll( list ) might be helpful).

[Havard]

Thank you so much for your reply.

Unfortunately there is a problem with using pointers.
This little program illustrates this:

#include <QtCore/QCoreApplication>
#include <emmintrin.h>
 
class myClass {
 
public:
       myClass();
       ~myClass();
       __m128i O;
 
};
 
myClass::myClass()
{
     //sets the O to 0 bits.
       O = _mm_set_epi32 (0x00000000,0x00000000,0x00000000,0x00000000);
}
 
myClass::~myClass()
{
}
 
int main(int argc, char *argv[])
{
   QCoreApplication a(argc, argv);
       QList<myClass *> list;
       list.append(new myClass());
 
   return a.exec();
}

#include <QtCore/QCoreApplication>
#include <emmintrin.h>

class myClass {

public:
       myClass();
       ~myClass();
       __m128i O;

};

myClass::myClass()
{
     //sets the O to 0 bits.
       O = _mm_set_epi32 (0x00000000,0x00000000,0x00000000,0x00000000);
}

myClass::~myClass()
{
}

int main(int argc, char *argv[])
{
   QCoreApplication a(argc, argv);
       QList<myClass *> list;
       list.append(new myClass());

   return a.exec();
}

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Because I am using SSE2 instructions, the program crashes... However, if instead use: list[20]; there is no problem. But using *list[20]; the program crashes in the same manner.
If I replace: list.append(new myClass()); with list.append(&myClass()); it does not crash, but I don't think this is any good?

My question? How would I rewrite the program to allow for QList<myClass> list; instead of QList<myClass *> list;

Thank you!

Havard

[jacek]

Because I am using SSE2 instructions, the program crashes...

It doesn't crash on my system. Are there any error messages? What CPU do you have?

My question? How would I rewrite the program to allow for QList<myClass> list; instead of QList<myClass *> list;

Just change:

QList<myClass *> list;
list.append(new myClass());

QList<myClass *> list;
list.append(new myClass());

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to

QList<myClass> list;
list.append( myClass() );

QList<myClass> list;
list.append( myClass() );

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The default implementations of operator= and copy constructor will be enough for myClass.

[Havard]

I just wanted to say that the problem was finally solved, but turned out to be a lot more complex than I had expected.

Without going into too much detail, it turns out that there is a problem with aligning the 16 byte sse2 variables inside a c++ class with a microsoft compiler.

So jacek, I am guessing that you are not using a microsoft-compiler since you did not get any errors with the little test-program I posted. I am even guessing you are not using anything microsoft (like Visual Studio) at all...?

The solution was to overload the "new" operator to make it align them properly.

[Havard]

Here is a link with the fix, if anyone would be interested in using sse2 with classes: http://softwarecommunity.intel.com/i.../30231301.aspx

[jacek]

So jacek, I am guessing that you are not using a microsoft-compiler since you did not get any errors with the little test-program I posted. I am even guessing you are not using anything microsoft (like Visual Studio) at all...?

Yes, you are absolutely right.