Using qGreater<T> with custom objects ...

tmason101

Hello,

How would one go about using qGreater<T> from QtAlgorithms with a custom object?

Do I have to implement a specific operator?

Thank you.

SGaist

Hi,

You need to implement the corresponding operator > for your custom object. If you are using Qt 5, you are encourage to use std::greater directly

tarod.net

That member is obsolete in Qt 5.4:

http://doc.qt.io/qt-5/qtalgorithms-obsolete.html

Anyway, you should implement your own function to compare your objects. Here you have an example:

@bool caseInsensitiveLessThan(const QString &s1, const QString &s2)
{
return s1.toLower() < s2.toLower();
}

int doSomething()
{
QStringList list;
list << "AlPha" << "beTA" << "gamma" << "DELTA";
qSort(list.begin(), list.end(), caseInsensitiveLessThan);
// list: [ "AlPha", "beTA", "DELTA", "gamma" ]
}@

tmason101

Thanks, I wanted to use a "greater than" in conjunction with a sorting algorithm; should I only use "std" style iterators?

Also, can I use the std sorting algorithm with a QVector?