[R] Single character input without Enter

[Dieter Menne]

Dieter Menne wrote:
> 
> How do I wait for a single character input without terminating "Enter"?
> 


In case someone needs a solution for Windows, here it is. Compiled Dll from

http://www.menne-biomed.de/download/keystate.zip

Dieter

#dyn.unload("keystate.dll")
dyn.load("keystate.dll")

AsyncKeyState = function(vkey){
  state = 0
 .C("AsyncKeyState",as.integer(state),as.integer(vkey))[[1]]
}

ShiftKeyState = function(){
  state = 0
 .C("ShiftKeyState",as.integer(state))[[1]]
}

ControlKeyState = function(){
  state = 0
 .C("ControlKeyState",as.integer(state))[[1]]
}

PressedKey = function(){
  state = 0
 .C("PressedKey",as.integer(state))[[1]]
}


# while(TRUE){
#   Sys.sleep(1)
#   cat(PressedKey(),"\n")
#}

// C Program
#include <windows.h>
#include <R.h>
//#include <Rdefines.h>
//#include <R_ext/Error.h>

#define DLLIMPORT __declspec (dllexport) 
#define VK_A 0x41
#define VK_Z 0x5A 

DLLIMPORT void AsyncKeyState(int *state,int* vKey) {
   state[0] = GetAsyncKeyState(*vKey) <0;
}

DLLIMPORT void ControlKeyState(int *state) {
   state[0] = GetAsyncKeyState(VK_CONTROL) <0;
}

DLLIMPORT void ShiftKeyState(int *state) {
  state[0] = GetAsyncKeyState(VK_SHIFT) < 0 ;
}

DLLIMPORT void PressedKey(int *state) {
  byte keyState[256];
  GetKeyboardState(keyState);
  for (*state=VK_A; (*state) <= VK_Z; (*state)++)
    if (keyState[*state] & 0x80)
	return ;
  *state = 0;
}


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