C# 检查flowLayoutPanel在c中是否为空#
我想在flowLayoutPanel为空时显示错误标签,但我不知道如何检查flowLayoutPanel是否为空。这是我当前的代码:C# 检查flowLayoutPanel在c中是否为空#,c#,winforms,null,label,flowlayoutpanel,C#,Winforms,Null,Label,Flowlayoutpanel,我想在flowLayoutPanel为空时显示错误标签,但我不知道如何检查flowLayoutPanel是否为空。这是我当前的代码: private void flowLayoutPanel1_ControlRemoved(object sender, ControlEventArgs e) { if (flowLayoutPanel1.Controls == null) { customtoolwa
private void flowLayoutPanel1_ControlRemoved(object sender, ControlEventArgs e)
{
if (flowLayoutPanel1.Controls == null)
{
customtoolwarning.Visible = true;
}
else
{
customtoolwarning.Visible = false;
}
}
请帮忙
谢谢您遇到的问题是您正在检查
控件
中的null
以确定它是否为空。控件
属性永远不会是null
,而是非null,为空时长度为0。比如说
if (flowLayoutPanel1.Controls.Count == 0) {
// It's empty
}
基本上什么都没有,它做的事情完全相同——只是另一种书写方式:)
private void flowLayoutPanel1_ControlRemoved(object sender, ControlEventArgs e)
{
if (flowLayoutPanel1.Controls.Count > 0)
{
customtoolwarning.Visible = true;
}
else
{
customtoolwarning.Visible = false;
}
}
lblNoContacts.Visible = (flowLayoutPanel.Controls.Count == 0) ? true : false;