Reading char from stdin without waiting for input

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Reading char from stdin without waiting for input

 
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  #1
Aug 2nd, 2009
I'm seeing if it is possible to write a pong game only using standard C with maximum portability. I've worked out everything except user input. When the game is playing, If the user has no key pressed down, the paddle does not move but the ball should keep moving. I can only think of two way's of doing this. One is to get the user to hold down an extra key at all times. The other is to shut off the buffer on stdin using setvbuf(), which will hopefully make getchar() return EOF or NULL when no key is being pressed. Would these work? Does anyone have any other idea's?
Thanks.
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Re: Reading char from stdin without waiting for input

 
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Aug 2nd, 2009
I think you would have to look at the ncurses library .. or the pdcurses library for the Window's equivalent to avoid any platform specific requirements.
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Re: Reading char from stdin without waiting for input

 
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Aug 2nd, 2009
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Originally Posted by yellowSnow View Post
I think you would have to look at the ncurses library .. or the pdcurses library for the Window's equivalent to avoid any platform specific requirements.
That would be cheating. I want to see what can be done with standard C alone.
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Re: Reading char from stdin without waiting for input

 
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Aug 2nd, 2009
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Originally Posted by Hiroshe View Post
That would be cheating. I want to see what can be done with standard C alone.
Prepare to be disappointed.
http://c-faq.com/osdep/cbreak.html
Last edited by Dave Sinkula; Aug 2nd, 2009 at 2:07 pm.
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Re: Reading char from stdin without waiting for input

 
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  #5
Aug 2nd, 2009
I also had the same problem in past,
I think, if you are using Turbo C, under <dos.h>, there is a function called kbhit(), checks keyboard hit.
C Syntax (Toggle Plain Text) 
  1. while(1){
  2.                // Ball movement codes,
  3.                if(kbhit()){
  4.                //check input ASCII and move your paddle.
  5.  
  6.               }
  7.               //exiting loop conditions
  8. }
Last edited by deepugtm; Aug 2nd, 2009 at 2:34 pm.
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Re: Reading char from stdin without waiting for input

 
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  #6
Aug 2nd, 2009
kbhit() function is in conio.h library and conio.h is not a standard library which is not what Hiroshe want
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Re: Reading char from stdin without waiting for input

 
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Aug 2nd, 2009
Is it standard behaviour for a key just pressed to outpower a key being held down? ie. The user holds down the space bar for the whole game, and the "up" key out powers the spacebar? If not, than I guess I'll have a theird key for "stay still".
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Re: Reading char from stdin without waiting for input

 
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Aug 2nd, 2009
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Originally Posted by Hiroshe View Post
Is it standard behaviour for a key just pressed to outpower a key being held down? ie. The user holds down the space bar for the whole game, and the "up" key out powers the spacebar? If not, than I guess I'll have a theird key for "stay still".
As you saw in the link...
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Originally Posted by Dave Sinkula View Post
Prepare to be disappointed.
http://c-faq.com/osdep/cbreak.html
The standard behavior is to do nothing in particular for any keypress, save the return key.
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Only when the user is satisfied and presses the RETURN key (or equivalent) is the line made available to the calling program.
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Re: Reading char from stdin without waiting for input

 
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Aug 2nd, 2009
Hmm... Then I guess the best I can do in standard C is to pause the game and get the user input (up, down, still) befor continuing on.

I'm too stubborn. Maybe instead of the space bar, get the user to hold down return. Just write an input function that ignores '\n'. That way the stream continuously updates. Would this work? I'll try it at home.
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Re: Reading char from stdin without waiting for input

 
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  #10
Aug 2nd, 2009
Nope, It didn't work. When I hold down return and press a character, it wait's for the another return. Thanks for helping.
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