Understanding Unix/Linux Programming-用户程序：play_again1

1 /* play_again1.c
2  * purpuse: ask if user wants another play
3  * better : instant response without echo
4  * returns: 0 -> yes , 1 -> no
5  */
6
7  #include <stdio.h>
8  #include <stdlib.h>
9  #include <termios.h>
10
11  #define QUESTION "Do you want another play?"
12
13  int get_response(char *);
14  void set_crmode(void);
15  void tty_mode(int);
16
17  int main()
18  {
19      int response ;
20      tty_mode(0);   // save tty mode
21      set_crmode();
22      response = get_response(QUESTION);
23      tty_mode(1);   // restore tty mode
24      return response ;
25  }
26
27  int get_response(char * qiz)
28  {
29      int input ;
30      printf("%s(y/n)" , qiz);
31      while(1)
32      {
33          switch(input = getchar())
34          {
35              case 'y':
36              case 'Y':
37                 printf("\n");
38                 return 0 ;
39              case 'n':
40              case 'N':
41              case EOF:
42                 printf("\n");
43                 return 1 ;
44              default :
45                 printf("\nCannot understand %c" , input );
46                 printf("Please type y or no \n");
47          }
48      }
49  }
50
51 void set_crmode(void)
52 {
53     struct  termios ttystate ;
54     tcgetattr(0 , &ttystate);
55     ttystate.c_lflag &= ~ICANON ;   // No Buffering
56     ttystate.c_cc[VMIN] = 1 ;   //Get one char one time
57     tcsetattr( 0 , TCSANOW , &ttystate);
58 }
59
60 void tty_mode(int mode)
61 {
62     static struct termios original_mode ;// 设置静态结构体变量
63     if(mode == 0 )
64     {
65         tcgetattr( 0 , & original_mode);// 存储原有设置
66     }
67     else
68     {
69         //还原原有设置
70         if( tcsetattr(0 , TCSANOW , & original_mode) == -1 )
71         {
72             perror("Restore tty settings failed!\n");
73         }
74     }
75 }