c# - 集合被修改；枚举操作可能无法执行

Question

我有这段代码，如果玩家不活着，就会删除玩家，但我认为问题出在 foreach 循环上。我见过涉及制作新列表的解决方案，但我看不出如何将它应用到我的代码中。谁能解释一下？

private Dictionary<int, Player> numPlayers = new Dictionary<int, Player>();

private void CheckPlayers()
{
    foreach (Player player in numPlayers.Values)
    {
        if (!player.isAlive)
        {
            canvas.Children.Remove(player.hand);
            numPlayers.Remove(player.id); // breaks here
        }
    }
}

Answer 1

查询要删除的玩家集合:

var playersToDelete = numPlayers.Values.Where(p => !p.isAlive).ToList();

然后删除玩家:

foreach(var player in playersToDelete) {
    canvas.Children.Remove(player.hand);
    numPlayers.Remove(player.id);
}