linux系统kbhit的几种实现

 #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);
 
 }

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;