kbhit() probkem

Asked by Wojciech Guzinski

man kbhit shows:
...
       #include <graphics.h>

       int kbhit (void);
...
Why compilation failed?
undefined reference to `kbhit()'

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Wojciech Guzinski
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Manfred Hampl (m-hampl) said :
#1

From where did you get that manpage for kbhit? It seems wrong.

https://www.tutorialspoint.com/kbhit-in-c-language

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Wojciech Guzinski (wojtekg) said :
#2

Ubuntu graphics prowide it's own kbhit , here you are man page:
KBHIT(3) SDL-libgraph API KBHIT(3)

NAME
       kbhit - check for key-stroke

SYNOPSIS
   C function :
       #include <graphics.h>

       int kbhit (void);

   Scheme procedure :
            (kbhit)

DESCRIPTION
       kbhit() checks to see if a keystroke is currently available.

       Any available keystroke can be retrieved using getchar(3) or getch(3).

   Example:
       while(!kbhit()) /* Loops until a key is pressed */
       {
            .....
            .....
            .....
       }

       This function can be used both in graphics mode and plain text. For
       other functions related to textmode see graphicstext(3)

   Note :
       In text mode use getchar(3) (not getch(3)) to retrieve the keystroke
       since getch(3) flushes the input buffer before reading.

RETURN VALUE
       On success (if a keystroke is available) kbhit() returns the keystroke.
       If a keystroke is not available it returns 0.

SEE ALSO
       libgraph(7), initgraph(3), getchar(3),
       getch(0), graphicstext(3)

libgraph-1.x.x 11 AUGUST 2003 KBHIT(3)

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Manfred Hampl (m-hampl) said :
#3

Don't blame Ubuntu for broken foreign software.
Ubuntu does not contain libgraph, so "Ubuntu graphics prowide it's own kbhit , here you are man page:" can't be true.

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Manfred Hampl (m-hampl) said :
#4

Reading your other questions on Launchpad and following the links in them, it seems to me that the KBHIT(3) man pages that you quoted are part of http://download.savannah.gnu.org/releases/libgraph/libgraph-1.0.2.tar.gz
Definitely not part of Ubuntu.

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Wojciech Guzinski (wojtekg) said :
#5

OK, this is the only, I know, graphics library working with ubuntu, it woks perfect just this one function can't be used.
This is minor problem I just asked if anyone knows why.

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Manfred Hampl (m-hampl) said :
#6

Haven't you read my comments and the links provided?

https://www.tutorialspoint.com/kbhit-in-c-language explains that kbhit() needs "#include <conio.h>"

https://askubuntu.com/questions/525051/how-do-i-use-graphics-h-in-ubuntu describes other and more current graphics libraries, e.g. OpenGL (via GLUT) and libxbgi.

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Wojciech Guzinski (wojtekg) said :
#7

I know that regular (not graphics) programming require conio.h and stdio.h but man pages mislead me.
in man pages (grapicstext) is told that some i/o funttions are "hacked" for working in libgraph window:
DESCRIPTION :
       These are the normal scanf(3), printf(3), getchar(3), putchar(3) func‐
       tions hacked up to work in graphics mode (i.e. in the libgraph window).
Also man page for kbhit says include grapjics.h

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Manfred Hampl (m-hampl) said :
#8

How often do I have to repeat:
The error is not in a piece of software from Ubuntu, but from elsewhere - https://savannah.nongnu.org/projects/libgraph/

Ubuntu cannot change foreign software, you have to report your problem there.

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Wojciech Guzinski (wojtekg) said :
#9

OK, thanks.