\1. 首先将窗口属性KeyPreview设为true，如果属性对话框中找不到，就直接在代码里添加； \2. 添加KeyPress / KeyDown事件：
1、KeyPress 和KeyDown 、KeyPress之间的区别 1）KeyPress主要用来捕获数字(注意：包括Shift+数字的符号)、字母（注意：包括大小写）、小键盘等除了F1-12、SHIFT、Alt、Ctrl、Insert、Home、PgUp、Delete、End、PgDn、ScrollLock、Pause、NumLock、{菜单键}、{开始键}和方向键外的ANSI字符 KeyDown 和KeyUp 通常可以捕获键盘除了PrScrn所有按键(这里不讨论特殊键盘的特殊键） 2）KeyPress 只能捕获单个字符 KeyDown 和 KeyUp 可以捕获组合键。 3）KeyPress 可以捕获单个字符的大小写 4）KeyDown和KeyUp 对于单个字符捕获的KeyValue 都是一个值，也就是不能判断单个字符的大小写。 5）KeyPress 不区分小键盘和主键盘的数字字符。 KeyDown 和KeyUp 区分小键盘和主键盘的数字字符。 6）其中PrScrn 按键KeyPress、KeyDown和KeyUp 都不能捕获。
2、KeyPress事件
Winform文本框只能输入数字和退格键和小数点：
private void TextBox_KeyPress(object sender, KeyPressEventArgs e)
{
if (e.KeyChar != 8 && !Char.IsDigit(e.KeyChar) && e.KeyChar != '.')
{
e.Handled = true;
}
}
//或者
private void TextBox_KeyPress(object sender, KeyPressEventArgs e)
{
if (e.KeyChar != '\b' && !Char.IsDigit(e.KeyChar) && e.KeyChar != '.')
{
e.Handled = true;
}
}
3、KeyChar取值：
另外2个特殊ASCII码：回车=13，换行=10，退格=‘\b’ 或者 退格=8
4、KeyDown事件：
捕获单个按键：
private void Form1_KeyDown(object sender, KeyEventArgs e)
{
Keys key = e.KeyCode;
if (e.Control!=true)//如果没按Ctrl键
return;
switch (key)
{
case Keys.NumPad0:
//按下小键盘0以后
break;
case Keys.NumPad1:
//按下小键盘1以后
break;
case Keys.S:
//按下S键以后
break;
case Keys.Up:
//按下向下键以后
break;
}
}
捕获组合键（以全选为例）：
private void textBox1_KeyDown(object sender, KeyEventArgs e)
{
if (e.Control && e.KeyCode == Keys.A)
{
(sender as TextBox).SelectAll();
}
}
5、KeyCode取值： keycode 8 = BackSpace BackSpace keycode 9 = Tab Tab keycode 12 = Clear keycode 13 = Enter keycode 16 = Shift_L keycode 17 = Control_L keycode 18 = Alt_L keycode 19 = Pause keycode 20 = Caps_Lock keycode 27 = Escape Escape keycode 32 = space space keycode 33 = Prior keycode 34 = Next keycode 35 = End keycode 36 = Home keycode 37 = Left keycode 38 = Up keycode 39 = Right keycode 40 = Down keycode 41 = Select keycode 42 = Print keycode 43 = Execute keycode 45 = Insert keycode 46 = Delete keycode 47 = Help keycode 48 = 0 equal braceright keycode 49 = 1 exclam onesuperior keycode 50 = 2 quotedbl twosuperior keycode 51 = 3 section threesuperior keycode 52 = 4 dollar keycode 53 = 5 percent keycode 54 = 6 ampersand keycode 55 = 7 slash braceleft keycode 56 = 8 parenleft bracketleft keycode 57 = 9 parenright bracketright keycode 65 = a A keycode 66 = b B keycode 67 = c C keycode 68 = d D keycode 69 = e E EuroSign keycode 70 = f F keycode 71 = g G keycode 72 = h H keycode 73 = i I keycode 74 = j J keycode 75 = k K keycode 76 = l L keycode 77 = m M mu keycode 78 = n N keycode 79 = o O keycode 80 = p P keycode 81 = q Q at keycode 82 = r R keycode 83 = s S keycode 84 = t T keycode 85 = u U keycode 86 = v V keycode 87 = w W keycode 88 = x X keycode 89 = y Y keycode 90 = z Z keycode 96 = KP_0 KP_0 keycode 97 = KP_1 KP_1 keycode 98 = KP_2 KP_2 keycode 99 = KP_3 KP_3 keycode 100 = KP_4 KP_4 keycode 101 = KP_5 KP_5 keycode 102 = KP_6 KP_6 keycode 103 = KP_7 KP_7 keycode 104 = KP_8 KP_8 keycode 105 = KP_9 KP_9 keycode 106 = KP_Multiply KP_Multiply keycode 107 = KP_Add KP_Add keycode 108 = KP_Separator KP_Separator keycode 109 = KP_Subtract KP_Subtract keycode 110 = KP_Decimal KP_Decimal keycode 111 = KP_Divide KP_Divide keycode 112 = F1 keycode 113 = F2 keycode 114 = F3 keycode 115 = F4 keycode 116 = F5 keycode 117 = F6 keycode 118 = F7 keycode 119 = F8 keycode 120 = F9 keycode 121 = F10 keycode 122 = F11 keycode 123 = F12 keycode 124 = F13 keycode 125 = F14 keycode 126 = F15 keycode 127 = F16 keycode 128 = F17 keycode 129 = F18 keycode 130 = F19 keycode 131 = F20 keycode 132 = F21 keycode 133 = F22 keycode 134 = F23 keycode 135 = F24 keycode 136 = Num_Lock keycode 137 = Scroll_Lock keycode 187 = acute grave keycode 188 = comma semicolon keycode 189 = minus underscore keycode 190 = period colon keycode 192 = numbersign apostrophe keycode 210 = plusminus hyphen macron keycode 211 = keycode 212 = copyright registered keycode 213 = guillemotleft guillemotright keycode 214 = masculine ordfeminine keycode 215 = ae AE keycode 216 = cent yen keycode 217 = questiondown exclamdown keycode 218 = onequarter onehalf threequarters keycode 220 = less greater bar keycode 221 = plus asterisk asciitilde keycode 227 = multiply division keycode 228 = acircumflex Acircumflex keycode 229 = ecircumflex Ecircumflex keycode 230 = icircumflex Icircumflex keycode 231 = ocircumflex Ocircumflex keycode 232 = ucircumflex Ucircumflex keycode 233 = ntilde Ntilde keycode 234 = yacute Yacute keycode 235 = oslash Ooblique keycode 236 = aring Aring keycode 237 = ccedilla Ccedilla keycode 238 = thorn THORN keycode 239 = eth ETH keycode 240 = diaeresis cedilla currency keycode 241 = agrave Agrave atilde Atilde keycode 242 = egrave Egrave keycode 243 = igrave Igrave keycode 244 = ograve Ograve otilde Otilde keycode 245 = ugrave Ugrave keycode 246 = adiaeresis Adiaeresis keycode 247 = ediaeresis Ediaeresis keycode 248 = idiaeresis Idiaeresis keycode 249 = odiaeresis Odiaeresis keycode 250 = udiaeresis Udiaeresis keycode 251 = ssharp question backslash keycode 252 = asciicircum degree keycode 253 = 3 sterling keycode 254 = Mode_switch
6、如何获取键盘按钮的keyChar值（keyCode同理）
private void Form1_KeyPress(object sender, KeyPressEventArgs e)
{
char Key_Char = e.KeyChar;//判断按键的 Keychar
MessageBox.Show(((int)(Key_Char)).ToString());//转成整数显示
}
