Simulating key presses in your program with keybd_event function

Oct 11, 2009 | 42Gears Team

Out of need or curiosity you might want to know how to send key presses from your native application. The core of the solution involves calling keybd_event() function which has the following prototype.

VOID keybd_event(BYTE bVk, BYTE bScan, DWORD dwFlags, DWORD dwExtraInfo);

bVk is the virtual-key code of the character. bScan is the hardware scan code. dwFlags is an important field. If KEYEVENTF_KEYUP is specified in dwFlags field, the key is being released. If not specified, the key is being pressed.

Here is a function which simulates pressing of alphanumeric characters. See winuser.h for all available virtual key codes.

void SendStringKeys(char* pszChars)
while (*pszChars != NULL)
if ( (*pszChars >= ‘A’) && (*pszChars <= 'Z') ) keybd_event(VK_SHIFT, 0, KEYEVENTF_SILENT, 0); keybd_event(toupper(*pszChars), 0, KEYEVENTF_SILENT, 0); keybd_event(toupper(*pszChars), 0, KEYEVENTF_KEYUP|KEYEVENTF_SILENT, 0); if ( (*pszChars >= ‘A’) && (*pszChars <= 'Z') ) keybd_event(VK_SHIFT, 0, KEYEVENTF_KEYUP|KEYEVENTF_SILENT, 0); pszChars++; } }

And here is an example of how to call SendStringKeys function.

int _tmain(int argc, _TCHAR* argv[])
SendStringKeys(“Hello World.”);
return 0;

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