小编Hea*_*amd的帖子

我真的很惊讶这个问题没有真正的答案.例如,我有一个foreach循环迭代队列(我正在使用.Net版本)foreach队列中究竟发生了什么？它是否像标准枚举器一样迭代？或者它是否使用该Dequeue()功能.

为清楚起见:

Queue<int> q = new Queue<int>();
foreach(int i in q)
{
    // what happens in this loop?
}

我有一个具有自定义样式的组合框，但下拉项呈现在屏幕左上角的 0,0 处。

<Style x:Key="CustomNetworkComboBox" TargetType="ComboBox">
        <Setter Property="ScrollViewer.HorizontalScrollBarVisibility" Value="Auto"/>
        <Setter Property="ScrollViewer.VerticalScrollBarVisibility" Value="Auto"/>
        <Setter Property="ScrollViewer.CanContentScroll" Value="true"/>
        <Setter Property="MinWidth" Value="175"/>
        <Setter Property="Height" Value="22"/>
        <Setter Property="OverridesDefaultStyle" Value="True"/>
        <Setter Property="Visibility" Value="Hidden" />
        <Setter Property="Background" Value="Transparent" />
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="ComboBox">
                    <Grid>
                        <ToggleButton Name="ToggleButton" Template="{StaticResource NetworkComboBoxToggleButton}" Grid.Column="2" Focusable="false" IsChecked="{Binding Path=IsDropDownOpen,Mode=TwoWay,RelativeSource={RelativeSource TemplatedParent}}" ClickMode="Press">
                        </ToggleButton>
                        <ContentPresenter Name="ContentSite" Content="{TemplateBinding SelectionBoxItem}" ContentTemplate="{TemplateBinding SelectionBoxItemTemplate}" ContentTemplateSelector="{TemplateBinding ItemTemplateSelector}" Margin="3,3,23,3" VerticalAlignment="Center" HorizontalAlignment="Left"/>
                        <TextBox x:Name="PART_EditableTextBox" 
                                     Foreground="{StaticResource Black13}" Style="{x:Null}" Template="{StaticResource ComboBoxTextBox}"
                                     HorizontalAlignment="Left" VerticalAlignment="Center" Margin="3,3,23,3"
                                     Focusable="True" Background="{x:Null}" Visibility="Hidden" IsReadOnly="True" BorderBrush="{x:Null}"/>
                        <Popup Name="PART_Popup"  IsOpen="{TemplateBinding IsDropDownOpen}" AllowsTransparency="True" …