MSDN: WM_KEYDOWN The WM_KEYDOWN message is posted to the window with the keyboard focus when a nonsystem key is pressed. A nonsystem key is a key that is pressed when the alt key is not pressed. WM_KEYDOWN nVirtKey = (int) wParam; // virtual-key code lKeyData = lParam; // key data
Parameters nVirtKey Value of wParam. Specifies the virtual-key code of the nonsystem key. lKeyData Value of lParam. Specifies the repeat count, scan code, extended-key flag, context code, previous key-state flag, and transition-state flag, as shown in the following table. Value Description 0–15 Specifies the repeat count for the current message. The value is the number of times the keystroke is auto-repeated as a result of the user holding down the key. If the keystroke is held long enough, multiple messages are sent. However, the repeat count is not cumulative. 16–23 Specifies the scan code. The value depends on the original equipment manufacturer (OEM). 24 Specifies whether the key is an extended key, such as the right-hand alt and ctrl keys that appear on an enhanced 101- or 102-key keyboard. The value is 1 if it is an extended key; otherwise, it is 0. 25–28 Reserved; do not use. 29 Specifies the context code. The value is always 0 for a WM_KEYDOWN message. 30 Specifies the previous key state. The value is 1 if the key is down before the message is sent, or it is 0 if the key is up. 31 Specifies the transition state. The value is always 0 for a WM_KEYDOWN message.
WM_KEYDOWN
The WM_KEYDOWN message is posted to the window with the keyboard focus when a nonsystem key is pressed. A nonsystem key is a key that is pressed when the alt key is not pressed. WM_KEYDOWN
nVirtKey = (int) wParam; // virtual-key code
lKeyData = lParam; // key data
Parameters
nVirtKey
Value of wParam. Specifies the virtual-key code of the nonsystem key.
lKeyData
Value of lParam. Specifies the repeat count, scan code, extended-key flag, context code, previous key-state flag, and transition-state flag, as shown in the following table. Value Description
0–15 Specifies the repeat count for the current message. The value is the number of times the keystroke is auto-repeated as a result of the user holding down the key. If the keystroke is held long enough, multiple messages are sent. However, the repeat count is not cumulative.
16–23 Specifies the scan code. The value depends on the original equipment manufacturer (OEM).
24 Specifies whether the key is an extended key, such as the right-hand alt and ctrl keys that appear on an enhanced 101- or 102-key keyboard. The value is 1 if it is an extended key; otherwise, it is 0.
25–28 Reserved; do not use.
29 Specifies the context code. The value is always 0 for a WM_KEYDOWN message.
30 Specifies the previous key state. The value is 1 if the key is down before the message is sent, or it is 0 if the key is up.
31 Specifies the transition state. The value is always 0 for a WM_KEYDOWN message.
WPARAM wParam = (WPARAM)'C';
LPARAM lParam = 0x412e0001; //01000001 00101110 00000000 00000001
其中00101110 = 0x2e 表示Ctrl键
SendMessage(hwnd, WM_KEYDOWN,wParam, lParam);
实际上最简单的方法可以通过VC的工具SPY++来查看。
另外spy++显示，如果要完整模拟Ctrl+C的按键过程，应该发送5次消息，如下：
1：WM_KEYDOWN nVirtKey:VK_CONTROL cRepeat:1 ScanCode:1D fExtended:0 fAltDown:0 fRepeat:0 fUp:0
2：WM_KEYDOWN nVirtKey:'C' cRepeat:1 ScanCode:2E fExtended:0 fAltDown:0 fRepeat:0 fUp:0
3：WM_CHAR chCharCode:'' (3) cRepeat:1 ScanCode:2E fExtended:0 fAltDown:0 fRepeat:0 fUp:0
4：WM_KEYUP nVirtKey:'C' cRepeat:1 ScanCode:2E fExtended:0 fAltDown:0 fRepeat:1 fUp:1
5：WM_KEYUP nVirtKey:VK_CONTROL cRepeat:1 ScanCode:1D fExtended:0 fAltDown:0 fRepeat:1 fUp:1