在C#中检查flowLayoutPanel是否为空

Question

我希望在我的flowLayoutPanel为空时显示一个错误标签，但我不知道如何检查flowLayoutPanel是否为空。这是我的当前代码：

private void flowLayoutPanel1_ControlRemoved(object sender, ControlEventArgs e)
        {
            if (flowLayoutPanel1.Controls == null)
            {
                customtoolwarning.Visible = true;
            }
            else
            {
                customtoolwarning.Visible = false;
            }
        }

Please Help,

Thanks

- Chris Bacon

Answer 1

private void flowLayoutPanel1_ControlRemoved(object sender, ControlEventArgs e)
        {
            if (flowLayoutPanel1.Controls.Count > 0)
            {
                customtoolwarning.Visible = true;
            }
            else
            {
                customtoolwarning.Visible = false;
            }
        }

- Ali Tarhini

Answer 2

你遇到的问题是你在检查 Controls 是否为空时使用了 null。然而，当 Controls 为空时，它的值不会为 null，而是非空且长度为0。例如：

if (flowLayoutPanel1.Controls.Count == 0) {
  // It's empty
}

- JaredPar

Answer 3

lblNoContacts.Visible = (flowLayoutPanel.Controls.Count == 0) ? true : false;

- Chriz

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基本上没有什么区别，它只是另一种写法而已 :) - Chriz