一，用select

#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);

}

 

二，用非阻塞io

#include <stdio.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;

}

int main(void)

{

while(!kbhit())

puts(“Press a key!”);

printf(“You pressed ‘%c’!/n”, getchar());

return 0;

}