>>405 Cならこれでいける
#include<stdio.h>
#include<conio.h>
#define KEYCODE_ENTER 0x0D
#define KEYCODE_EXTEND 0xE0
#define KEYCODE_RIGHT 'M'
#define KEYCODE_LEFT 'K'
void print_menu(int menu_item){
  if(!menu_item) printf("\r[continue] finish ");
  else printf("\r continue [finish]");
}
int main(void){
  int menu_item=0;
  int keycode;
  while(1){
    print_menu(menu_item);
    keycode=getch();
    if(keycode==KEYCODE_ENTER) break;
    if(keycode==KEYCODE_EXTEND){
      keycode=getch();
      switch(keycode){
        case KEYCODE_RIGHT: menu_item=1; break;
        case KEYCODE_LEFT: menu_item=0; break;
      }
    }
  }
  printf("Your choice is %d\n", menu_item);
  return 0;
}