if (kbhit())
{
    ch1 = getch();
    if (ch1 != '\0')
    {
            // process a normal keystroke
    }
    else
    {
        ch2 = getch();    // get the arrow or function key
        switch(ch2)
        {
                // process the arrow or function key
        }
    }
}

/******************************* 0026.c *******************************/
/*                                                                    */
/* Date:        September 22, 2006                                    */
/* Author:      diode                                                 */
/*              ndweiler@mchsi.com                                    */
/* Purpose:	    To practice checking for arrow keys being pressed     */
/*              in a header file                                      */
/*                                                                    */
/**********************************************************************/
 
#include <stdio.h>
#include <stdlib.h>
#include <conio.h>
#include <string.h>
#include <process.h>
#include <ctype.h>
 
#define STRING_LENGTH 100
#define ARROW_KEY_NONE 0
#define ARROW_KEY_UP 1
#define ARROW_KEY_DOWN 2
#define ARROW_KEY_LEFT 3
#define ARROW_KEY_RIGHT 4
#define ARROW_KEY_POSSIBLE 5
 
// BEGINNING OF PROTOTYPES
 
void settext(void);
void getline(char * str2);
void showoutput(char * str2);
int checkarrowkey(char key);
 
// BEGINNING OF PROGRAM
 
int main()
{
  char strexit[STRING_LENGTH];
  char strquit[STRING_LENGTH];
  char holdtextline[STRING_LENGTH];
 
  system("cls");
  holdtextline[0] = '\0';
  getline(holdtextline);
  showoutput(holdtextline);
  printf("\n");
 
  return 0;
}
// END OF PROGRAM
 
// BEGINNING OF FUNCTIONS
 
void settext(void)
{
  char text;
  text = getch();                           // holds the output on screen
}
 
void getline(char * str2)
{
  char str1[STRING_LENGTH];
  int num = 0;
  int checkkey = 0;                         // used to check for special keys
 
  printf("Enter your text:");               // instructs you to enter something
 
  do                                        // starts loop for input
  {
    if (num == STRING_LENGTH)
      {
        break;                              // exits when the string fills up
      }
      else
        {
          str1[num] = getch();              // puts a char into 'str'
        }
 
    if ((str1[num] == '\b') && (num <= 0))  // starts the backspace handler
    {                                       // if you're at the beginning...
                                            // do nothing
    }
    else                                    // but if everything's alright...
      {
 
/////////////////////////////////////////////////////////////////
// This is where I check to see if the user typed an arrow
/////////////////////////////////////////////////////////////////
        if((str1[num] == '\0') && (num >= 0))
          {
            num++;
            goto last;
          }
          else
            {
              if((num > 0) && (str1[num - 1] == '\0') && (str1[num] != '\0'))
                {
                  checkkey = checkarrowkey(str1[num]);
 
                  switch(checkkey)
                  {
                    case ARROW_KEY_UP:
                      printf("\nYou pressed the UP arrow key!");
                      return;
 
                    case ARROW_KEY_DOWN:
                      printf("\nYou pressed the DOWN arrow key!");
                      return;
 
                    case ARROW_KEY_LEFT:
                      printf("\nYou pressed the LEFT arrow key!");
                      return;
 
                    case ARROW_KEY_RIGHT:
                      printf("\nYou pressed the RIGHT arrow key!");
                      return;
 
                    default:
                      return;
                  }
                }
            }
 
/////////////////////////////////////////////////////////////////
// This ends where I check to see if the user typed an arrow
/////////////////////////////////////////////////////////////////
 
        printf("%c", str1[num]);            // echoes your char to the screen
      }
 
    str1[num] = tolower(str1[num]);         // converts it to lowercase
 
    if ((str1[num] == '\b') && (num >= 1))  // removes the last-typed char
      {                                     // from the screen and from the
        printf(" \b");                      // string
        str1[num - 1] = '\0';               //
        num = num - 1;                      //
      }
    else
      {
        if (str1[num] != '\b')              // if everything is alright...
          {                                 //
            num++;                          // it increments 'num' by 1
          }
      }
 
last:
 
  } while(str1[num-1] != 0x0D);             // loops until ENTER is hit
 
  str1[num - 1] = '\0';                     // create the NULL string char
 
  strcpy(str2, str1);                       // copy 'str1' to 'str2'
}
 
void showoutput(char * str2)      // beginning of 'showoutput'
{
  int length = strlen(str2);                // sets 'length' to the length of
                                            // the string 'str2'
 
  printf("\n\nYour text was '%s' ", str2);  // outputs 'str2' to screen
 
 
  printf("\n'%s' is %d characters long",// outputs 'str2' and its
         str2, length);                 // length to the screen
}
 
int checkarrowkey(char key)
{
  int whichkey = 0;
  char str1 = '\0';
  //char str2[STRING_LENGTH];
 
  str1 = key;
 
  switch(str1)
    {
      case 'H':
        whichkey = ARROW_KEY_UP;
        return whichkey;
 
      case 'P':
        whichkey = ARROW_KEY_DOWN;
        return whichkey;
 
      case 'K':
        whichkey = ARROW_KEY_LEFT;
        return whichkey;
 
      case 'M':
        whichkey = ARROW_KEY_RIGHT;
        return whichkey;
 
      default:
        return 0;
    }
}