QList qt5.3中的比较项目

Question

I am trying to compare the items in a QList. Here is the old way to do it using QPtrCollection but this cannot be used in versions after qt3 (as far as I'm aware).

class gnyComponentList:public QList<gnyComponent>
{
protected:
    virtual int compareItems ( QPtrCollection::Item item1, QPtrCollection::Item item2 )
    { return (((gnyComponent *)item1)->getID()).compare(((gnyComponent *)item2)->getID());}
};

I can't figure out what a good way of doing this in Qt5.3 might be?

Answer 1

You can use the std::equal algorithm on QList objects, as in:

#include <QList>
#include <QString>

#include <algorithm> // for std::equal

struct Person
{
    QString firstName;
    QString lastName;
};

int main()
{
    QList<Person> personsA, personsB;
    // Populate personsA and personsB
    bool equal = std::equal( personsA.begin(), personsA.end(),
                             personsB.begin(),
                             []( const Person &a, const Person & b ) {
                                return a.firstName == b.firstName;
                             } );
}

Answer 2

This is a simple one, which compares every item without sorting. Here is the code.

bool TeachTab::isTwoStringListEqual(const QStringList &dst,
                                const QStringList &src) {
  if (dst.size() != src.size())
    return false;
  for (int i = 0; i < dst.size(); ++i) {
    if (dst.value(i) != src.value(i)) {
      return false;
    }
  }
  return true;
}