about input in hello

[huang]

hi,dear all:
 

   if I want to get some input in the "hello" example, what should I do?
I simply use "scanf()", but it does not work!
   my main.c is as below:

#include <l4/sys/types.h>
#include <l4/sys/syscalls.h>
#include <l4/sys/ipc.h>

#include <stdio.h>

int main(int argc, char **argv)
{
  l4_threadid_t th;
  l4_msgdope_t result;
  l4_umword_t d1, d2;
  int choice;

  printf("Hello World\n");

  th = l4_myself();

  for (;;)
    {
      printf("hello: My thread-id is %x.%x\n", th.id.task, th.id.lthread);

      scanf("%d",&choice);
      if(choice==0) return 0;	  
    }
}