getchar() returns the same value (27) for up and down arrow keys

Question

So for the up key on the keyboard, I get 27, surprisingly for the down key I also get 27. I need my program to behave differently on the up and down key, and I can't seem to figure it out. I am using Linux, and need it to work for Linux.

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
int main()
{
    int c = getchar();

    if(c==27)
    {
        printf("UP");
    }

    if(c==28)
    {
        printf("DOWN");
    }

} 

Answer 1

The 27 implies that you're getting ANSI escape sequences for the arrows. They're going to be three-character sequences: 27, 91, and then 65, 66, 67, 68 (IIRC) for up, down, right, left. If you get a 27 from a call to getchar(), then call it twice more to get the 91 and the number that determines what arrow key was pressed.

As someone else mentioned, this is platform-specific, but you may not care.

Answer 2

Here is the program , which is written to use ncurses library , and display the arrow keys pressed.

#include<ncurses.h>

int main()
{
int ch;

/* Curses Initialisations */
initscr();
raw();
keypad(stdscr, TRUE);
noecho();

printw("Press E to Exit\n");

while((ch = getch()) != 'E')
{
    switch(ch)
    {
    case KEY_UP:         printw("\nUp Arrow");
                break;
    case KEY_DOWN:      printw("\nDown Arrow");
                break;
    case KEY_LEFT:      printw("\nLeft Arrow");
                break;
    case KEY_RIGHT:     printw("\nRight Arrow");
                break;
    default:    
                printw("\nThe pressed key is %c",ch);

    }
}

printw("\n\Exiting Now\n");
endwin();

return 0;
}

while compiling , you have to link to the ncurses library.

gcc main.c -lncurses

Here is a tutorial to help you get started with ncurses.