C＃：无效的转换异常

Question

谁能帮我这个，我真的很努力工作，如何更正此错误：

public class ModDataGridView : DataGridView 
    { 
    } 

public partial class Form1 : Form 
{ 
    public Form1() 
    { 
     InitializeComponent(); 
    } 

    private void button1_Click(object sender, EventArgs e) 
    { 
     ModDataGridView dgv2 = new ModDataGridView(); 
     pnl.Controls.Add(dgv2); //pnl is a Panel type 
     foreach (ModDataGridView item in pnl.Controls) 
     { 
      txt.AppendText(item.GetType().ToString()); 
     } 

    } 
} 

型

'System.InvalidCastException' occurred in Test.exe

Additional information: Unable to cast object of type 'System.Windows.Forms.DataGridView' to type 'Test.ModDataGridView'.

Answer 1

使用未处理的异常anonymouse型var

foreach (var item in pnl.Controls) 
    { 
     if(item.GetType() == typeof(ModDataGridView)) 
     { 
      txt.AppendText(item.GetType().ToString()); 
     } 
    } 

Answer 2

你确定你只想增加了ModDataGridView？

你可能会使用的OfType<>()

public partial class Form1 : Form 
{ 
    public Form1() 
    { 
     InitializeComponent(); 
    } 

    private void button1_Click(object sender, EventArgs e) 
    { 
     ModDataGridView dgv2 = new ModDataGridView(); 
     pnl.Controls.Add(dgv2); //pnl is a Panel type 
     foreach (ModDataGridView item in pnl.Controls.OfType<ModDataGridView>()) 
     { 
      txt.AppendText(item.GetType().ToString()); 
     } 

    } 
} 

---

如果你想所有控件，使用一个基类：

public partial class Form1 : Form 
{ 
    public Form1() 
    { 
     InitializeComponent(); 
    } 

    private void button1_Click(object sender, EventArgs e) 
    { 
     ModDataGridView dgv2 = new ModDataGridView(); 
     pnl.Controls.Add(dgv2); //pnl is a Panel type 
     foreach (Control item in pnl.Controls) 
     { 
      txt.AppendText(item.GetType().ToString()); 
     } 

    } 
}