Getting additions and removals from two lists

main.cpp

#include <QCoreApplication>

#include <QDebug>

void printChanges(QList<QString> existingList, QList<QString> newList)
{
    std::sort(existingList.begin(), existingList.end());
    std::sort(newList.begin(), newList.end());

    QList<QString> added;
    std::set_difference(newList.constBegin(), newList.constEnd(),
        existingList.constBegin(), existingList.constEnd(), std::back_inserter(added));
    qDebug() << "added" << added;

    QList<QString> removed;
    std::set_difference(existingList.constBegin(), existingList.constEnd(),
        newList.constBegin(), newList.constEnd(), std::back_inserter(removed));
    qDebug() << "removed" << removed << "\n";
}

int main(
    int argc, char *argv[])
{
    QCoreApplication a(argc, argv);

    // Expected output:
    // added QList()
    // removed QList()
    printChanges({ "a", "b" }, { "a", "b" });

    // Expected output:
    // added QList("c")
    // removed QList()
    printChanges({ "a", "b" }, { "a", "b", "c" });

    // Expected output:
    // added QList()
    // removed QList("b")
    printChanges({ "a", "b" }, { "a" });

    // Expected output:
    // added QList()
    // removed QList()
    printChanges({ "a", "b" }, { "b", "a" });

    return 0;
}