You have to make two calls to the getch()function when you read extended characters (57888)

SUMMARY

In Microsoft C, when reading extended characters you must make two calls to getch() because the first call returns a value indicating that the key is an extended character. The second call returns the actual key code. When you are reading an extended character, the first return value will be either 0xE0 or 0x00, depending on which extended key is pressed.

Sample Code

#include <stdio.h>
#include <conio.h>

void main(void)
{
    int ch, scan;

    do {
        ch = getch();    /* 1st getch() gets ASCII code */ 
        printf("Character is %d\n", ch);
           if (ch == 0x00 || ch == 0XE0)  { /* if extended key */ 
            scan = getch();  /* 2nd getch() gets "scan code" */ 
            printf("\tExtended character:  scan is %d\n", scan);
        }
    }  while (ch != 27);    /* exit loop on ESC */ 
}

For a discussion of keystrokes and scan codes, refer to "The New Peter Norton Programmer's Guide to the IBM PC & PS/2," by Peter Norton and Richard Wilton.