#include <windows.h>



int checkbox_id = 156;

//prototype of window procedure

LRESULT WINAPI myProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam); 



int APIENTRY WinMain(HINSTANCE, HINSTANCE, LPSTR, int)

{

	MSG msg;

	HWND myDialog = CreateWindowEx(

		0,WC_DIALOG,"My Window",WS_OVERLAPPEDWINDOW | WS_VISIBLE,

		400,100,200,200,NULL,NULL,NULL,NULL

	);

	//create the checkbox

	HWND txt = CreateWindowEx(

		0,"BUTTON","Check and uncheck me",BS_AUTOCHECKBOX | WS_VISIBLE | WS_CHILD,

		10,50,170,25,myDialog,(HMENU)checkbox_id,NULL,NULL

	);

	

	SetWindowLong(myDialog, DWL_DLGPROC, (long)myProc);



	while(GetMessage(&msg,NULL,0,0)) { 

		TranslateMessage(&msg); 

		DispatchMessage(&msg);

	}



	return 0; 	

}



LRESULT WINAPI myProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam) 

{

	if(message == WM_CLOSE) 

		PostQuitMessage(0);		

		

	//check if checkbox was check or unchecked

	if(message==WM_COMMAND && LOWORD(wParam)==checkbox_id) 

	{

		//First get handle of checkbox by casting lParam to HWND

		HWND checkbox_handle = (HWND)lParam;

		//send message BM_GETCHECK to check box to retrieve its current state        

		int state = SendMessage(checkbox_handle,BM_GETCHECK,0,0);

		

		if(state == BST_CHECKED) //yes it is checked

			MessageBox(hwnd,"It hs checked","Message",0);

		else

			;//it has been Unchecked

	}

	

	return 0; 

}