[Qt4] QSORT

[jane]

Hi, I've got a problem using qSort, when I reimplement LessThan :

In my Vertical class:

QList<Plane *> Vertical::planes;     //static list of Plane objects
 
bool lessThan( const Plane *plane1, const Plane *plane2) 
{
    Plane *me = Vertical::getPlanes().at(0);
    return(plane1->close(me->getPosition()) < plane2->close(me->getPosition()));
}
 
 
void Vertical::sortL(const QString &str)
{
    QList <Plane *> list; 
    qCopy(planes.begin()+1, planes.end(), list.begin());
    qSort(list.begin(), list.end(),lessThan);
                  .......
}
 
QList<Plane *> Vertical::getPlanes()  {
    return planes;
}
 
 
and in the Plane class :
 
double Plane::close(const QPoint &p) const
{
    return  (sqrt((double)((p.x()-position.x())^2 + (p.y()-position.y())^2)));
}

QList<Plane *> Vertical::planes;     //static list of Plane objects

bool lessThan( const Plane *plane1, const Plane *plane2) 
{
    Plane *me = Vertical::getPlanes().at(0);
    return(plane1->close(me->getPosition()) < plane2->close(me->getPosition()));
}


void Vertical::sortL(const QString &str)
{
    QList <Plane *> list; 
    qCopy(planes.begin()+1, planes.end(), list.begin());
    qSort(list.begin(), list.end(),lessThan);
                  .......
}

QList<Plane *> Vertical::getPlanes()  {
    return planes;
}


and in the Plane class :

double Plane::close(const QPoint &p) const
{
    return  (sqrt((double)((p.x()-position.x())^2 + (p.y()-position.y())^2)));
}

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And the compiler says that qsort does not look as a function that takes 2 arguments, and gives me some lines number erros in qalgorithms.h
Any ideas ???

[lauranger]

qStableSort, may be ?

[jane]

no, I ve got the same problem, but thanks

[jacek]

And the compiler says that qsort does not look as a function that takes 2 arguments, and gives me some lines number erros in qalgorithms.h

Could you post the exact error message?

[jane]

Ok no problem, but as I m french, it s not in english, here it is :

c:\Qt\src\corelib\tools\qalgorithms.h(341): error C2064: le terme ne correspond pas à une fonction qui prend les arguments 2

which means the term does not match with a function which takes the arguments 2
the line in qalgorithms.h :
if (!lessThan(*hi, *lo)) {

[jane]

Ok,
problem solved :
I have no idea why but I tried turning the lessThan function static and now it works ???!!!! which I don t really understands but it do compile, so ....

[gfunk]

qSort cannot take a member function pointer as an argument, which is a very different type than regular function pointers. Your function is really defined as:
bool Vertical::lessThan( const Plane *plane1, const Plane *plane2)

I think this article might explain it better:
http://www.informit.com/guides/conte...lus&seqNum=142