whoffman@topaz.UUCP (03/20/87)
Hello,
I am seeking a way to tell whether or not a key has been pressed on
a keyboard. i.e something like this:
while (1)
{ ...statements....
if "a key has been pressed" {...statements}
...statements...}
the problem i keep running into is that getc,getchar etc..all WAIT for
a key to be pressed. I would just like to see IF one has been pressed.
Any help on this would be greatly appreciated. Thanks in advance...
bill.
William R. Hoffman
Arpa: whoffman@topaz.rutgers.edu or whoffman@red.rutgers.edu
Uucp: ...{harvard | seismo | pyramid}!rutgers!topaz!whoffmantr@thumper.UUCP (03/20/87)
In article <10260@topaz.RUTGERS.EDU>, whoffman@topaz.UUCP writes: > > Hello, > > I am seeking a way to tell whether or not a key has been pressed on > a keyboard. i.e something like this: > > while (1) > { ...statements.... > if "a key has been pressed" {...statements} > ...statements...} > > the problem i keep running into is that getc,getchar etc..all WAIT for > a key to be pressed. I would just like to see IF one has been pressed. > Any help on this would be greatly appreciated. Thanks in advance... > > William R. Hoffman Well, I gather you are using a minicomputer, so the routine I use won't work for you. In MS-DOS, the Microsoft and Lattice compilers give you functions called kbkit() which take no arguments and return either TRUE or FALSE. Too bad because they work. Anyway, why don't you use getchar(), check for EOF, and if there is a character, unget() the character? This would push it back onto the input stream. Tom Reingold INTERNET: tr@bellcore.com -------- UUCP: ---- watmath!clyde!bellcore\ ucbvax\ \ lll-lcc\ ihnp4!mhuxt!ulysses!faline!flash!tr seismo!rutgers!mit-eddie!allegra/ -- Tom Reingold Internet: tr@bellcore.com Uucp: ..!allegra!ulysses!faline!flash!tr
edw@ius2.cs.cmu.edu.UUCP (03/22/87)
In article <10260@topaz.RUTGERS.EDU>, whoffman@topaz.UUCP writes: > > Hello, > > I am seeking a way to tell whether or not a key has been pressed on > a keyboard. i.e something like this: > > while (1) > { ...statements.... > if "a key has been pressed" {...statements} > ...statements...} > > the problem i keep running into is that getc,getchar etc..all WAIT for > a key to be pressed. I would just like to see IF one has been pressed. > Any help on this would be greatly appreciated. Thanks in advance... > > William R. Hoffman If you are on a unix os you can make a call to "select" and it will tell you whether a file descriptor or list of files descriptor are ready to read from, write to, or have excecption pending (See manual entry for select for more details.) Note also you can get the file descriptor for a pointer to a file (FILE *fp) with the macro fileno which is defined in stdio.h. Also, if you are on a Unix os, you will want to make the appropriate call to ioctl or stty so that characters are made available to your process as soon as they are type, instead of buffering them until a new line is type from the terminal (cbreak on or off, one of the two). Eddie Wyatt
levy@ttrdc.UUCP (03/22/87)
In article <10260@topaz.RUTGERS.EDU>, whoffman@topaz.RUTGERS.EDU (The Skiing Fanatic!) writes: < I am seeking a way to tell whether or not a key has been pressed on < a keyboard. i.e something like this: < < while (1) < { ...statements.... < if "a key has been pressed" {...statements} < ...statements...} < < the problem i keep running into is that getc,getchar etc..all WAIT for < a key to be pressed. I would just like to see IF one has been pressed. < Any help on this would be greatly appreciated. Thanks in advance... < William R. Hoffman Please tell us your machine and compiler when making net requests like this. The answer differs depending on whether the environment is a PC (and upon the PC compiler), System V, Berserkely Unix, VMS, IBM/CMS, etc. Stuff having to do with single key strokes is system dependent and may require special terminal setups and/or exotic I/O calls and/or etc. -- |------------dan levy------------| Path: ..!{akgua,homxb,ihnp4,ltuxa,mvuxa, | an engihacker @ | vax135}!ttrdc!ttrda!levy | at&t computer systems division | Disclaimer: these views are all MINE! |--------skokie, illinois--------| MINE! MINE! HAHAHAHAHAHAHAHAHA!!!!!!
chris@mimsy.UUCP (Chris Torek) (03/22/87)
In article <1073@ius2.cs.cmu.edu> edw@ius2.cs.cmu.edu (Eddie Wyatt) writes: >If you are on a unix os you can make a call to "select" ... As this points out, the answer is system dependent. In particular, select() exists only on 4.2BSD and V8 derived systems. (I understand System VII ... no, make that System V release 3 [cannot change a standard! :-) ] for the Vax has something equivalent, but harder to use.) Under 4.1BSD, one can use the FIONREAD ioctl. Under System III one can fiddle with VTIME or something like that. -- In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 7690) UUCP: seismo!mimsy!chris ARPA/CSNet: chris@mimsy.umd.edu
decot@hpisod2.UUCP (03/24/87)
> As this points out, the answer is system dependent. In particular, > select() exists only on 4.2BSD and V8 derived systems. (I understand > System VII ... no, make that System V release 3 [cannot change a > standard! :-) ] for the Vax has something equivalent, but harder > to use.) Under 4.1BSD, one can use the FIONREAD ioctl. Under > System III one can fiddle with VTIME or something like that. Select(2) also exists in HP-UX, a SVID-conforming operating system. Dave Decot hpda!decot
josh@hi.UUCP (03/26/87)
-- Josh Siegel, Project Asst. | Internet: siegel@hc.dspo.gov Electrical and Computer Eng. | UUCP: hc!siegel University of New Mexico | (505) 277-1611 (Lab) Albuquerque, New Mexico 87131 | (505) 277-2497 (Home)
jv@mhres.UUCP (03/28/87)
In article <2550008@hpisod2.HP.COM>, decot@hpisod2.HP.COM (Dave Decot) writes: > Select(2) also exists in HP-UX, a SVID-conforming operating system. > > Dave Decot > hpda!decot Yes it exists. But after we re-booted our HP9000 model 530 it told us that the new select(2) system call would not work on our multiplexors ... and these are the only terminal lines we have. -- Johan Vromans @ Multihouse Research, Gouda, the Netherlands usenet: ..{seismo!}mcvax!mhres!jv