Thread: kbhit() for linux.

from my post on http://cboard.cprogramming.com/showt...ighlight=kbhit

Code:

#include <stdio.h>
#include <termios.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/time.h>

void changemode(int);
int  kbhit(void);
int main(void)
{
  int ch;
  changemode(1);
  while ( !kbhit() )
  {
    putchar('.');
  }

  ch = getchar();

  printf("\nGot %c\n", ch);

  changemode(0);
  return 0;
}

void changemode(int dir)
{
  static struct termios oldt, newt;

  if ( dir == 1 )
  {
    tcgetattr( STDIN_FILENO, &oldt);
    newt = oldt;
    newt.c_lflag &= ~( ICANON | ECHO );
    tcsetattr( STDIN_FILENO, TCSANOW, &newt);
  }
  else
    tcsetattr( STDIN_FILENO, TCSANOW, &oldt);
}

int kbhit (void)
{
  struct timeval tv;
  fd_set rdfs;

  tv.tv_sec = 0;
  tv.tv_usec = 0;

  FD_ZERO(&rdfs);
  FD_SET (STDIN_FILENO, &rdfs);

  select(STDIN_FILENO+1, &rdfs, NULL, NULL, &tv);
  return FD_ISSET(STDIN_FILENO, &rdfs);

}

Originally Posted by quzah

Why don't you just use the curses library to do it?

Quzah.

Im considering that now seeing as im using curses throughtout my program anyway.

Thats for the code guys.

Cant seem to implement either of those examples.

Code:

		changemode(1);

		if( kbhit() )
		{
			ch = getchar();
			printf("\nGot %c\n", ch);

			if ( ch == 'c')
			return 1;

			changemode(0);

		}

This never seems to return to the calling function.
Do you know any function i can use fom curses for this?

Thanks

Code:

...
	while (  *ai_mode != FOLLOW_LINE )
	{
		printf("\n\njoymode\n\n");

		move_motors_with_stick(device, subdevice_an_zero, subdevice_an_one, x_scale, y_scale, x_min_read, y_min_read, x_max_read, y_max_read);

		read_digital(subdevice_dig, device, &digital_input);

		/* if MARCO has gone over a line, we leave the loop and return to the menu, selecting the follow_ilne module */
		if (( digital_input & LEFT_SENSOR ) || ( digital_input & RIGHT_SENSOR ))
		{
			*ai_mode = FOLLOW_LINE;
		}

		retval = bla();

		printf("...................%d.....................", retval);

		if ( retval == 1 )
		{
			puts("BLA");
			return 0;
		}

	}

	return 1;

}
int bla()
{
  	int ch;
  	changemode(1);

	if ( kbhit() )
	{

		changemode(0);
		return 1;

	}


	changemode(0);
  	return 0;
}

for some reason, after "BLA" is outputted on the console, it doesnt return to the calling function. Why is this?

thanks

Code:

#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <termios.h>
#include <unistd.h>
#include <fcntl.h>

int kbhit(void)
{
  struct termios oldt, newt;
  int ch;
  int oldf;

  tcgetattr(STDIN_FILENO, &oldt);
  newt = oldt;
  newt.c_lflag &= ~(ICANON | ECHO);
  tcsetattr(STDIN_FILENO, TCSANOW, &newt);
  oldf = fcntl(STDIN_FILENO, F_GETFL, 0);
  fcntl(STDIN_FILENO, F_SETFL, oldf | O_NONBLOCK);

  ch = getchar();

  tcsetattr(STDIN_FILENO, TCSANOW, &oldt);
  fcntl(STDIN_FILENO, F_SETFL, oldf);

  if(ch != EOF)
  {
    ungetc(ch, stdin);
    return 1;
  }

  return 0;
}


main( int argc, char** argv )
{
	char *input = argv[0];
	int nomor = argc;
	pid_t pid = 0;
	/* set stuff up */
	/* accept command line args */
	
	pid = fork();
	if( pid == 0 ){
		/* this is the "background" process.  Execute process loop here */
		int x=0;	
		while(1)
		{
			if(kbhit())
			  printf("you hit keyboard");
		}
	}
	else {
		/* "foreground" process exits */
		exit(0);
	}
}

why this kbhit doesnt work in child process??