小编med*_*r44的帖子

我可以像KeyValuePair在方法中那样解构为 lambda 参数吗？那么，是否有可能写这样的东西：ToDictionaryforeach

dict.ToDictionary((key, value) => key, (key, value) => 2*value);

我试图向 QGraphicsScene 添加几个项目，但在调用scene->addItem(new Bonus(Bonus::BonusType::coin, randPoint, pixels, parent));应用程序输出后出现此消息：QGraphicsScene::addItem: item has already been added to this scene。
我做错了什么？
代码：

for(int i = 0; i < coinsCount; ) {
    QPoint randPoint(random() % g->getWidth(),
                     random() % g->getHeight());

    if(g->getType(randPoint) != Graph::wall && !usedPoints.contains(randPoint)) {
        scene->addItem(new Bonus(Bonus::BonusType::coin, randPoint, pixels, parent));
        usedPoints.push_back(randPoint);
        i++;
    }
}