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From: tshiono@cv.sony.co.jp (Toru SHIONO)
Newsgroups: comp.lang.perl
Subject: Re: One Character
Message-ID: <TSHIONO.94Jan24124717@aquarius.cv.sony.co.jp>
Date: 24 Jan 94 12:47:17 GMT
References: <gbrekke-200194085537@dude.mr.net>
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In-reply-to: gbrekke@MR.Net's message of 20 Jan 94 14:55:36 GMT

In article <gbrekke-200194085537@dude.mr.net>
	gbrekke@MR.Net (Gregg D. Brekke) writes:

:How do you grab just _ONE_ character from STDIN without a carriage return? 
:
:I'm converting a bunch of utilities I wrote in C and would like to make 
:them independent of outside routines.
:
:This would be akin to setting raw mode in C to read one character.  
:i.e. The C code reads:
:
:char one_char ()
:{
: 	struct sgttyb orig, myttyb;
:  char c;
:
:	 ioctl (fileno(stdin), TIOCGETP, &myttyb)
: 	orig = myttyb;
:  myttyb.sg_flags |= (RAW);
:	 ioctl (fileno(stdin), TIOCSETP, &myttyb)
:	 read(0, &c, 1);
:	 ioctl (fileno(stdin), TIOCSETP, &orig)
:  return (c);
:}

Perl version may look like:

require 'sys/ioctl.ph';

sub one_char {
    ioctl(STDIN, &TIOCGETP, $sgo);
    $sgn = $sgo;
    @array = unpack('ccccs', $sgn);
    $array[4] |= &RAW;
    $sgn = pack('ccccs', @array);
    ioctl(STDIN, &TIOCSETP, $sgn);
    read(STDIN, $c, 1);
    ioctl(STDIN, &TIOCSETP, $sgo);
    $c;
}

It will be better to replace '&RAW' with '&CBREAK' and write
a proper signal handler to trap interrupts.
--
Toru "devil-may-care" Shiono          Sony Corporation, JAPAN



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