C#中设置textbox限制条件的方法

/// <summary>
/// 屏蔽数字textbox的其他字符串
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
public virtual void tBoxNumbers_KeyDown(object sender, KeyEventArgs e)
{
    e.SuppressKeyPress = true;

    switch (e.KeyCode)
    {
 case Keys.D0:
 case Keys.D1:
 case Keys.D2:
 case Keys.D3:
 case Keys.D4:
 case Keys.D5:
 case Keys.D6:
 case Keys.D7:
 case Keys.D8:
 case Keys.D9:
 case Keys.NumPad0:
 case Keys.NumPad1:
 case Keys.NumPad2:
 case Keys.NumPad3:
 case Keys.NumPad4:
 case Keys.NumPad5:
 case Keys.NumPad6:
 case Keys.NumPad7:
 case Keys.NumPad8:
 case Keys.NumPad9:
 case Keys.Back:
 case Keys.OemPeriod:
 case Keys.Delete:
 case Keys.Decimal:
     e.SuppressKeyPress = false;
     break;
 default:
     break;
    }
}

public virtual void tBoxNumbers_KeyPress(object sender, KeyPressEventArgs e)
{
    TextBox tBox = sender as TextBox;
    char c = e.KeyChar;

    if (c.ToString().Equals("."))
    {
 if (tBox.Text.Length <= 0)
     e.Handled = true;           //小数点不能在第一位    
 else
 {
     float f;
     float oldf;
     bool b1 = false, b2 = false;
     b1 = float.TryParse(tBox.Text, out oldf);
     b2 = float.TryParse(tBox.Text + e.KeyChar.ToString(), out f);
     if (b2 == false)
     {
  if (b1 == true)
      e.Handled = true;
  else
      e.Handled = false;
     }
 }
    }
}

/// <summary>
/// 屏蔽数字textbox的其他字符串
/// </summary>
/// <param name="tbox">要屏蔽的textbox</param>
public virtual void ShieldNumberTextBoxOtherKeys(TextBox tbox)
{
    tbox.ImeMode = ImeMode.Disable;
    tbox.KeyDown += tBoxNumbers_KeyDown;
    tbox.KeyPress += tBoxNumbers_KeyPress;
}

#endregion