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read key from keybord in c

Hallo,

is there any ansi-c-function, that just read one char from keyboard and returns this value? Functions I know are getc(), fgetc() and getchar(); but all this functions read from stdin until carry return and sends every char to stdout like scanf(). I need function, that do following:

- waits until one key is pressed,
- reads value of this key from stdin,
- does not output this char to stdout,
- returns ascii value,

So I need something like PASCAL's readkey();

Thanks for help :)

You have to change the terminal to non-buffered I/O. You can do this with the termios() function. The man page might not give you enough details but there's a ton of sample code doing it if you do a google search search on "non-buffered termios".

there's something like it in
the ncurses library i think.

billy

Hi,

this might work:

Code:

/* readchar.c

 * Written by René Schleicher <rs@bofh.name>

 */

#include <termios.h>

#include <string.h>

#include <unistd.h>

#include <stdio.h>



int

main (void)

{

  char c;

  struct termios new_kbd_mode;

  struct termios g_old_kbd_mode;



  /* put keyboard (stdin) in raw, unbuffered mode */

  tcgetattr (0, &g_old_kbd_mode);

  memcpy (&new_kbd_mode, &g_old_kbd_mode, sizeof (struct termios));



  new_kbd_mode.c_lflag &= ~(ICANON | ECHO);

  new_kbd_mode.c_cc[VTIME] = 0;

  new_kbd_mode.c_cc[VMIN] = 1;

  tcsetattr (0, TCSANOW, &new_kbd_mode);





  if (read (0, &c, 1) != 1)

    {

      fprintf (stderr, "read() failed\n");

      _exit (-1);

    }



  /* set back into old mode */

  tcsetattr (0, TCSANOW, &g_old_kbd_mode);



  printf ("-%c-\n", c);



  return 0;

}

I used the following code in an application:

Code:

#include <stdio.h>

#include <unistd.h>

#include <termios.h>

#include <sys/ioctl.h>



struct termio original_termio;



void enterInputMode()

{

        //Settings for stdin (source: svgalib):

        int fd = fileno(stdin);

        struct termio zap;

        ioctl(fd, TCGETA, &original_termio);

        zap = original_termio;

        zap.c_cc[VMIN] = 0;

        zap.c_cc[VTIME] = 0;

        zap.c_lflag = 0;

        ioctl(fd, TCSETA, &zap);

}



void leaveInputMode()

{

        //Restore original stdin

        int fd = fileno(stdin);

        ioctl(fd, TCSETA, &original_termio);

}



char readKey()

{

        int fd = fileno(stdin);



        char c = '\0';

        int e = read(fd, &c, 1);

        if (e == 0) c = '\0';



        return c;

}

Call enterInputMode() before doing any readKey() calls, and leaveInputMode() after you're finished, to leave the terminal as bash etc. expect it to be. readKey returns '\0' if there's no key pressed. To wait for a key, do something like this:

Code:

char c = '\n'; //Just anything not equal to '\0'

while(c != '\0') c = readKey();

Special keys, like the arrow keys or the function keys, return "escape sequences". You can use the cat program without arguments to discover these. To scan them, you should do several readKey calls to check for escape sequences whenever the escape character is detected. Most terminal programs (xterm, konsole, PuTTY etc.) generate the same sequences, but to do things correctly you should read the termcap database. I never did this, but if you really want to do it, then it might be easier to use the ncurses library, which does everything for you.

What about kbhit()
Is there something like this or i am wrong ??

That a DOS thing from the Borland compilers.
See these forum threads on how make a function like kbhit() for Linux:

http://www.linuxquestions.org/questi...archid=1682323