C++ _getch() read multiple values - c++

Question

#define KEY_UP 72
#define KEY_DOWN 80
#define KEY_LEFT 75
#define KEY_RIGHT 77
int main()
{
int c = 0;
while (c != 27) //esc key code
{
c = 0;
switch (c = _getch())
{
case KEY_UP:
cout << endl << "Up" << endl;//key up
break;
case KEY_DOWN:
cout << endl << "Down" << endl; // key down
break;
case KEY_LEFT:
cout << endl << "Left" << endl; // key left
break;
case KEY_RIGHT:
cout << endl << "Right" << endl; // key right
break;
default:
cout << endl << "null" << endl;
break;
}
}
return 0;
}
The output should be
Up
Down
Left
Right
But what I get is
null
Up
null
Down
null
Left
null
Right
Based on the output, the program will read in other key code which I have no idea what is that before reading the actual key code, I didn't have any cin before this, why? any solution?

Answer 1

Had you chosen to read the fine manual, you would have encountered this statement:
When reading a function key or an arrow key, each function must be called twice; the first call returns 0 or 0xE0, and the second call returns the actual key code.
That's how you can tell when 72 means arrow-up and when it's the letter H (which happens to have an ASCII code of 72).

Answer 2

Changes made:
I removed default from the switch statement. It was causing the null prints.
Furthermore I've also added kbhit() and #define KEY_ESC 27, and moved getch() to ouside of the switch statement.
#define KEY_UP 72
#define KEY_DOWN 80
#define KEY_LEFT 75
#define KEY_RIGHT 77
#define KEY_ESC 27
#include <conio.h>
#include <stdio.h>
#include <windows.h>
#include <iostream>
using namespace std;
int main()
{
int c = 0;
while ( c!= KEY_ESC ) //esc key code is 27
{
if (kbhit()) {
c = getch();
switch ( c )
{
case KEY_UP:
cout << endl << "Up" << endl;//key up
break;
case KEY_DOWN:
cout << endl << "Down" << endl; // key down
break;
case KEY_LEFT:
cout << endl << "Left" << endl; // key left
break;
case KEY_RIGHT:
cout << endl << "Right" << endl; // key right
break;
}//switch
}//if
}//while
return 0;
}