How does the file descriptor work on given C code

[amskape]

I am new to C programming file descriptor concept , working in an already developed code base. I have no idea regarding the following file descriptor concept .

if (misc->playing == -1 || misc->cd_type != CDIO_DISC_MODE_CD_DA)
      {
         fd_set rfds;
         struct timeval tv;
 
         FD_ZERO (&rfds);
         FD_SET (0, &rfds);
         tv.tv_sec = 0;
         tv.tv_usec = 100000;
// pause till a key has been pressed or 0.1 misc->elapsed_seconds are elapsed
         select (1, &rfds, NULL, NULL, &tv);
      } // if
 

Please waiting for your fast response.

Thanks
Anes P A

[weaknessforcats]

Have you read about:

select (1, &rfds, NULL, NULL, &tv);

The select function appears in various forms of socket programming. I know there is a Wikipedia for the UNIX version of this function written by the Open Group which has a lot more info than I can post here.

Check it out.

[donbock]

Type fd_set and functions FD_ZERO(), FD_SET(), and select() are not part of the C Standard. Presumably they are provided by the operating system.
What operating system are you using?

Your operating system may vary, but typically the return value from select() is useful.

[amskape]

Dear donbock,
I am using Ubuntu 15.10. The application is a C written program running in ubuntu...
advise me

Thanks
Anes

[donbock]

Your code snippet is very similar to the example in the Ubuntu man page for select, et.al.. What questions remain after reading this?