Simulating a Ctrl-V keystroke in Win32 (C or C++) using SendInput

This short example program simulates pressing Ctrl-V on the keyboard (the Windows shortcut for “Paste”) once every second. It’s a modified version of an earlier example I posted on keystroke simulation using the Win32 SendInput function. What’s different this time is that the effect of holding down the control key while pressing another key is simulated.

Basically, each “Ctrl-V” is simulated in four steps:

1. Press the Control key
2. Press the V key
3. Release the V key
4. Release the Control key

I compiled this example using the gcc compiler (from MinGW), but I think it should work fine in Visual C++ (or similar).

//
// ctrlv.c - Simulates pressing Ctrl-V once a second
//
// Written by Ted Burke - last updated 18-10-2012
//
// To compile with MinGW:
//
//		gcc -o ctrlv.exe ctrlv.c
//
// To run the program:
//
//		ctrlv.exe
//

// Because the SendInput function is only supported in
// Windows 2000 and later, WINVER needs to be set as
// follows so that SendInput gets defined when windows.h
// is included below.
#define WINVER 0x0500
#include <windows.h>

int main()
{
	// Create a generic keyboard event structure
	INPUT ip;
	ip.type = INPUT_KEYBOARD;
	ip.ki.wScan = 0;
	ip.ki.time = 0;
	ip.ki.dwExtraInfo = 0;

	while(1)
	{
		// Press the "Ctrl" key
		ip.ki.wVk = VK_CONTROL;
		ip.ki.dwFlags = 0; // 0 for key press
		SendInput(1, &ip, sizeof(INPUT));

		// Press the "V" key
		ip.ki.wVk = 'V';
		ip.ki.dwFlags = 0; // 0 for key press
		SendInput(1, &ip, sizeof(INPUT));

		// Release the "V" key
		ip.ki.wVk = 'V';
		ip.ki.dwFlags = KEYEVENTF_KEYUP;
		SendInput(1, &ip, sizeof(INPUT));

		// Release the "Ctrl" key
		ip.ki.wVk = VK_CONTROL;
		ip.ki.dwFlags = KEYEVENTF_KEYUP;
		SendInput(1, &ip, sizeof(INPUT));
		
		Sleep(1000); // pause for 1 second
	}

	// We won't actually ever reach this point
	return 0;
}

To try it out:

1. Open Notepad,
2. Type a word and then copy it to the clipboard,
3. Switch to a console window and run ctrlv.exe,
4. Switch back to Notepad and you should see the word pasted repeatedly, once a second.
5. Switch back to the console and press Ctrl-C to stop ctrlv.exe.