Roman

#include <iostream>
#include <map>
#include <string>
#include <vector>
using namespace std;

template<typename Key, typename Val>
class Map
{
  map<Key, Val> values;
  vector<Key> index;
public:
  // ...
  auto operator[](int i)
  {
    return values[index[i]];
  }
  // ...
  void insert(const pair<Key, Val>& val)
  {
    values[val.first] = val.second;
    index.push_back(val.first);
  }
  // ...
};

int main()
{
  Map<int, string> mp;

  mp.insert({3, "three"});
  mp.insert({42, "forty two"});
  mp.insert({2, "two"});
  mp.insert({4, "four"});

  for(int i = 0; i < 4; ++i)
  {
    cout << mp[i] << "\n";
  }
}

QSqlDatabase db = QSqlDatabase::addDatabase("QSQLITE", "memdb");
db.setDatabaseName(":memory:");

if (!db.open())
{
    qDebug() << db.lastError().text();
    // std::exit(1);
}

QSqlQuery q("", db);
q.exec("create table Universities (id integer primary key, Location varchar, Population integer)");
q.exec("insert into Universities values (0, 'MSK', 12000000)");
q.exec("insert into Universities values (1, 'NSK', 1600000)");
q.exec("insert into Universities values (2, 'SPB', 6000000)");
q.exec("insert into Universities values (3, 'PRM', 1000000)");

int sz = ui->tableWidget->rowCount();

QString queryString = "SELECT * FROM Universities WHERE Location IN (";
for(int i = 0; i < sz; ++i)
{
    queryString += "?,";
}
queryString.back() = ')';

QSqlQuery query(queryString, db);

for(int i = 0; i < sz; ++i)
{
  query.bindValue(i, ui->tableWidget->item(i, 0)->text());
}

if (!query.exec())
{
  qDebug() << query.lastError().text();
  // std::exit(1);
}

while(query.next())
{
  qDebug() << query.value(0).toInt() << " "
           << query.value(1).toString() << " "
           << query.value(2).toInt() << "\n";
}

QSqlQuery query;
query.prepare("SELECT * FROM Universities WHERE Location IN (?)");

int sz = ui->tableWidget->rowCount();

QVariantList values;
for(int i = 0; i < sz; ++i)
{
  values << ui->tableWidget->item(i, 0)->text();
}
    
query.addBindValue(values);
if (!query.execBatch())
{
  qDebug() << query.lastError();
}

QStandardItemModel *model = new QStandardItemModel();
for (auto& x : tx->AddrsTo) 
{
  Qstring s(x.c_str()); 
  QStringList items = s.split(';');
  int sz = items.size();
  for(int i = 0; i < sz; ++i)
  {
    model->setItem(0, i, new QStandardItem(items[i]));
  }
}
this->findChild<QTableView*>("Adresses_tableView")->setModel(model);

#include <QObject>
#include <QVector>
class Foo: public QObject
{
    Q_OBJECT
    Q_PROPERTY(QVector<bool> b READ getData WRITE setData)
public:
    Foo()
    {
        m_b.resize(30);
        for(auto &b:m_b)
        {
            b = true;
        }
    }
    QVector<bool> getData()
    {
        return m_b;
    }
    void inv()
    {
        for(auto &b:m_b)
        {
            b = !b;
        }
    }
    void setData(QVector<bool> b)
    {
        m_b = b;
    }

private:
     QVector<bool> m_b;
};

class Bar: public QObject
{
    Q_OBJECT
    Q_PROPERTY(QVector<bool> b WRITE setData)
public:
    Bar(){};
    void printData()
    {
        for(auto &b:m_b)
        {
            qDebug() << b << ' ';
        }
    }
    void setData(QVector<bool> b)
    {
        m_b = b;
    }
private:
     QVector<bool> m_b;
};

int main(int argc, char *argv[])
{
    Foo foo;
    Bar bar;
    bar.setData(foo.getData());
    bar.printData();
    
    qDebug() << "modify\n";

    foo.inv();
    bar.setProperty("b", foo.property("b"));
    bar.printData();
}