Pressing ENTER constantly in an EOF loop alternative

Question

I'm new to programming, so bear with me. Also using GNU/Linux.

So I'm trying to create a loop that will check if I have used CTRL+D to end the loop to a MySQL connection, but at the same time constantly check the connection to the server.

while ((c = getchar()) != EOF)
{
    if (mysql_ping(conn) == 1)
    {
        fprintf(stderr, "Error: %s\n", mysql_error(conn));
    }
}

A problem is that I constantly have to press ENTER to check if the connection is still alive, however I want it to automatically check the connection to the MySQL server while still having the EOF feature so people can close the connection.

I know why this is happening, I'm just not sure how to fix it. Are there any other inbuilt functions or possible external libraries that I require?

What you need is a non-blocking check. Possible duplicate: http://stackoverflow.com/questions/11472043/non-blocking-getch — Wintermute, Dec 23 '13 at 09:43

Buddhima Gamlath · Answer 1 · 2013-12-23T10:00:52.217

3

The problem is getchar() being a blocking function. That means, whenever you call getchar(), it waits until a key is pressed.

Try something like this.

For linux... You need to install ncurses library.

 #include <curses.h> 

 ...

 int key;
 nodelay(stdscr, TRUE);
 while (1) {
      if ((key = getch()) == ERR) {  // no key is pressed...
        if(mysql_ping(conn) == 1){
          fprintf(stderr, "Error: %s\n", mysql_error(conn));
        }
      }else { // key is pressed...
          if (key == EOF) break;
      }
 }

For windows...

#include <conio.h>

...


while(1){
   if (_kbhit()){
      int key = _getch();
      if (key == EOF) break;
   } 
   if(mysql_ping(conn) == 1){
     fprintf(stderr, "Error: %s\n", mysql_error(conn));
   }
}

edited Dec 23 '13 at 10:00

answered Dec 23 '13 at 09:42

Buddhima Gamlath

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Sadly I'm not under Windows, I should specify this in the main post. Sorry. – Gingerbeer Dec 23 '13 at 09:50
1

@Gingerbeer Reason to rejoice I would say :-) – meaning-matters Dec 23 '13 at 09:51
@Gingerbeer: In that case you may need to have a look at http://hughm.cs.ukzn.ac.za/~murrellh/os/notes/ncurses.html – Buddhima Gamlath Dec 23 '13 at 09:54
@Gingerbeer: I edited the answer to include a linux fix... :) – Buddhima Gamlath Dec 23 '13 at 10:01
1

@bgamlath Slightly works, it now checks during the loop but it won't detect the keys now. I think I'll have to modify the software using the Ncurses library. Thank you for your help though! – Gingerbeer Dec 23 '13 at 11:06

Pressing ENTER constantly in an EOF loop alternative

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