linux系统kbhit的几种实现

风火石

一，用select

1. #include <stdio.h>
   
2. #include <termios.h>
   
3. #include <unistd.h>
   
4. #include <sys/types.h>
   
5. #include <sys/time.h>
   
6. 
   
7. void changemode(int);
   
8. int kbhit(void);
   
9. int main(void)
   
10. {
    
11. int ch;
    
12. changemode(1);
    
13. while ( !kbhit() )
    
14. {
    
15. putchar('.');
    
16. }
    
17. 
    
18. ch = getchar();
    
19. 
    
20. printf("\nGot %c\n", ch);
    
21. 
    
22. changemode(0);
    
23. return 0;
    
24. }
    
25. 
    
26. void changemode(int dir)
    
27. {
    
28. static struct termios oldt, newt;
    
29. 
    
30. if ( dir == 1 )
    
31. {
    
32. tcgetattr( STDIN_FILENO, &oldt);
    
33. newt = oldt;
    
34. newt.c_lflag &= ~( ICANON | ECHO );
    
35. tcsetattr( STDIN_FILENO, TCSANOW, &newt);
    
36. }
    
37. else
    
38. tcsetattr( STDIN_FILENO, TCSANOW, &oldt);
    
39. }
    
40. 
    
41. int kbhit (void)
    
42. {
    
43. struct timeval tv;
    
44. fd_set rdfs;
    
45. 
    
46. tv.tv_sec = 0;
    
47. tv.tv_usec = 0;
    
48. 
    
49. FD_ZERO(&rdfs);
    
50. FD_SET (STDIN_FILENO, &rdfs);
    
51. 
    
52. select(STDIN_FILENO+1, &rdfs, NULL, NULL, &tv);
    
53. return FD_ISSET(STDIN_FILENO, &rdfs);
    
54. }

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二，用非阻塞io

1. #include <stdio.h>
   
2. #include <termios.h>
   
3. #include <unistd.h>
   
4. #include <fcntl.h>
   
5. int kbhit(void)
   
6. {
   
7. struct termios oldt, newt;
   
8. int ch;
   
9. int oldf;
   
10. tcgetattr(STDIN_FILENO, &oldt);
    
11. newt = oldt;
    
12. newt.c_lflag &= ~(ICANON | ECHO);
    
13. tcsetattr(STDIN_FILENO, TCSANOW, &newt);
    
14. oldf = fcntl(STDIN_FILENO, F_GETFL, 0);
    
15. fcntl(STDIN_FILENO, F_SETFL, oldf | O_NONBLOCK);
    
16. ch = getchar();
    
17. tcsetattr(STDIN_FILENO, TCSANOW, &oldt);
    
18. fcntl(STDIN_FILENO, F_SETFL, oldf);
    
19. if(ch != EOF)
    
20. {
    
21. ungetc(ch, stdin);
    
22. return 1;
    
23. }
    
24. return 0;
    
25. }
    
26. int main(void)
    
27. {
    
28. while(!kbhit())
    
29. puts("Press a key!");
    
30. printf("You pressed '%c'!/n", getchar());
    
31. return 0;
    
32. }

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