On the MAC, you need to fiddle with the terminal settings to turn off line buffering. (You can also turn off echo.) Once the terminal is setup correctly, you can use read
to get single characters from the keyboard.
In the sample code below, the kbsetup
function takes care of the terminal settings. The getkey
function checks for a key press, and returns the key if any, or '\0'
if no key was read. The main
function has a loop that prints the time once per second, and prints any key that the user presses. Press 'q'
to exit the program.
#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#include <time.h>
#include <termios.h>
#include <unistd.h>
static struct termios oldSettings;
void kbcleanup( void )
{
tcsetattr( 0, TCSAFLUSH, &oldSettings ); /* restore old settings */
}
void kbsetup( void )
{
tcgetattr( 0, &oldSettings );
struct termios newSettings = oldSettings;
newSettings.c_lflag &= ~ICANON; /* disable line-at-a-time input */
newSettings.c_lflag &= ~ECHO; /* disable echo */
newSettings.c_cc[VMIN] = 0; /* don't wait for characters */
newSettings.c_cc[VTIME] = 0; /* no minimum wait time */
if ( tcsetattr( 0, TCSAFLUSH, &newSettings ) == 0 ){
atexit( kbcleanup ); /* restore the terminal settings when the program exits */
} else {
fprintf( stderr, "Unable to set terminal mode\n" );
exit( 1 );
}
}
int getkey( void )
{
char c;
if ( read( STDIN_FILENO, &c, 1 ) == 0 )
return '\0';
else
return c;
}
int main( void )
{
int c;
kbsetup();
time_t start = time( NULL );
time_t previous = start;
for (;;)
{
usleep( 1000 );
time_t current = time( NULL );
if ( current != previous )
{
fprintf( stderr, "tick %3ld\r", current - start );
previous = current;
}
else if ( (c = getkey()) != '\0' )
{
if ( c == 'q' || c == 'Q' )
break;
printf( "\ngot char: 0x%02x", c );
if ( isprint( c ) )
printf( " '%c'", c );
printf( "\n" );
}
}
}