实现如下：

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Text.RegularExpressions;

using System.Threading.Tasks;

using System.Windows.Forms;

namespace PISS.View.CustomControl

{

public class LetterAndNum : TextBox

{

protected override void OnKeyPress(KeyPressEventArgs e)

{

base.OnKeyPress(e);

SetStandard(e);

}

private void SetStandard(System.Windows.Forms.KeyPressEventArgs e)

{

//只允许输入字母

Regex regex = new Regex(@"^([A-Za-z0-9]|[\b])+$");

MatchCollection mc = regex.Matches(e.KeyChar.ToString());

foreach (Match ma in mc)

{

e.Handled = false;

return;

}

e.Handled = true;

}

}

}