How to read a character at a time from STDIN without needing to press return key?

ruby-talk
1

In the following bit of code:

print STDIN.getc
STDOUT.flush

The code for whatever key I type isn't actually printed out until I go on to hit the return key. How can I have it printed as soon as I type a character key?

Thanks,
Ken

2

-------- Original-Nachricht --------

Datum: Thu, 4 Sep 2008 05:40:43 +0900
Von: Kenneth McDonald <kenneth.m.mcdonald@sbcglobal.net>
An: ruby-talk@ruby-lang.org
Betreff: How to read a character at a time from STDIN without needing to press return key?

In the following bit of code:

print STDIN.getc
STDOUT.flush

The code for whatever key I type isn't actually printed out until I go
on to hit the return key. How can I have it printed as soon as I type
a character key?

Thanks,
Ken

Dear Ken,

I found this thread : http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-talk/78856
about the same question ....

Best regards,

Axel

···

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3

Kenneth McDonald wrote:

In the following bit of code:

print STDIN.getc
STDOUT.flush

The code for whatever key I type isn't actually printed out until I go
on to hit the return key. How can I have it printed as soon as I type
a character key?

Thanks,
Ken

It's not in Ruby standard. Under Windows you can do it like this:

def read_char
  require "Win32API"
  Win32API.new("crtdll", "_getch", , "L").Call
end

Found here: Ruby Quiz - Sokoban (#5)

TPR.

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4

Hi,

At Thu, 4 Sep 2008 05:40:43 +0900,
Kenneth McDonald wrote in [ruby-talk:313786]:

In the following bit of code:

print STDIN.getc
STDOUT.flush

The code for whatever key I type isn't actually printed out until I go
on to hit the return key. How can I have it printed as soon as I type
a character key?

With io-console, you can do:

  print STDIN.getch

http://www.rubyist.net/~nobu/ruby/io-console.tar.bz2
http://www.rubyist.net/~nobu/ruby/io-console-0.2.gem

···

--
Nobu Nakada

5

Hi,

In the following bit of code:

print STDIN.getc
STDOUT.flush

The code for whatever key I type isn't actually printed out until I go on
to hit the return key. How can I have it printed as soon as I type a
character key?

On feasible operating systems you can install the "termios" gem.
Then say something like:

  class IO
    def nocanon
      term = Termios::getattr self
      term.c_lflag &= ~Termios::ICANON
      Termios::setattr self, Termios::TCSANOW, term
      yield
    ensure
      term.c_lflag |= Termios::ICANON
      Termios::setattr self, Termios::TCSANOW, term
    end
  end

  $stdin.nocanon do
    c = $stdin.getc
  end

Maybe you like to have a look at how I let the user enter
passwords: <http://bertram-scharpf.homelinux.com/src/password.rb&gt;\.

Good luck!

Bertram

···

Am Donnerstag, 04. Sep 2008, 05:40:43 +0900 schrieb Kenneth McDonald:

--
Bertram Scharpf
Stuttgart, Deutschland/Germany
http://www.bertram-scharpf.de

6

Hope that helps.

James Edward Gray II

···

On Sep 3, 2008, at 3:40 PM, Kenneth McDonald wrote:

In the following bit of code:

print STDIN.getc
STDOUT.flush

The code for whatever key I type isn't actually printed out until I go on to hit the return key. How can I have it printed as soon as I type a character key?