'''HiLo''' is a simple number-guessing game: for each guess, 
you get the answer "too high" or "too low", until you guess right.

With this game, you can explain how binary seaching works.

----
 #! /usr/bin/tclsh

 # HiLo.tcl - HaJo Gurt - 2005-06-20
 # Simple Guess-the-number - game
 #
 # !! Run this in tclsh84 - wish has a bug with "gets" !!
 # See also: http://wiki.tcl.tk/10794 - [gets workaround]

  proc input1 {prompt} {
  #: Get input from user
    puts -nonewline $prompt
    set n [gets stdin]   ;# implicit return
  }

  proc input {prompt} {
  #: Get input from user, accept only numbers
    set ok 0
    while {$ok==0} {
      puts -nonewline $prompt
      set n [gets stdin]
      set ok [string is integer -strict $n] 
      if {$ok==0} { puts "'$n' is invalid !\a" }  ;# "\a": bell
    }
    return $n
  }

  proc inputA {prompt} {
  #: Test: "Automatic" input, simulates user
    puts -nonewline $prompt
    incr ::x             ;# Global variable x
  }

  proc random { {range 100} } {
  #: Return a number in the range 0 .. $range-1
    return [expr {int(rand()*$range)}]
  }

 #########.#########=#########^#########+#########*#########_#########$#####

  proc HiLo { {Max 100} } {
  #: Play the game
   #set Secret 11   ;# Test
    set Secret [expr {[random $Max] +1 }]

    puts "Guess my number (1 .. $Max)"
    set Try  0
    while 1 {
      incr Try
      set Guess [ input "Your guess #$Try: " ]     ;# Test: Replace "input" with "inputA"
      if {$Guess <  $Secret} { puts "$Guess is too low"  }
      if {$Guess >  $Secret} { puts "$Guess is too high" }
      if {$Guess == $Secret} { puts "$Guess is correct - You needed $Try guesses."; break }
      if {$Try >= 12}        { puts "You won't guess it..."; break }   ;# Emergency-break
    }
    puts "Bye!"
  }
 #########.#########=#########^#########+#########*#########_#########$#####

  set x 0               ;# Test: starting value for inputA
  catch {console show}  ;# when running in wish: open console-window

 #HiLo 1024
  HiLo                  ;# default: 100
----
[HJG] It looks like the biggest problem with this program is the simple [gets] for reading from the user.
Even the FAQ at http://www.tcl.tk/man/tcl8.4/TclCmd/gets.htm and the tutorial at [tcltutorial] doesn't have useful information about this...

Is there a simpler way for "input" than [gets workaround], e.g. without a gui ?

[MG] If you're using wish / Tk and have a GUI, you could have an entry widget where it can entered, and print the messages to a (deactivated, so it can't be altered) text widget. The entry widget would also allow for easy validation of the input - in the above, for instance, you could enter text or other non-numeric data, which would still work as being greater/less than the number in question.

[HJG] I'm not sure what you mean, concerning ''gets''.  
In tclsh84 ''gets'' works fine, but in wish ''gets'' returns an empty string.

[LV] What operating system and version of Tcl are you using? My guess is that you are using Windows (or you are launching the Tk application from a menu or launch button where no stdin is available), because I've used gets and Tk together on Solaris and they worked okay if the user started the application up from a console that had stdin and stdout set up. I do remember reading about issues with stdin and stdout on Windows, and needing to ensure that a [console] was open for the user to see the information. I just tried the following:
===
# in a cygwin ksh xterm
$ cat tst.tk
#! wish
package require Tk

console show

puts "This is a test"
set ans [gets stdin]
puts $ans

button .e -text Exit -command {exit 0;}
$ wish tst.tk
This is a test
testing
testing
===
On the screen is a Tk console as well as a button . I press the button and the application terminates. So I see the stdout, I type in the stdin and the application sees it. And I see the Tk button. So it all seems to work on this Windows XP system, using ActiveTcl 8.4.10.1.

So I would like this behavior of ''gets'' under wish fixed, preferably with something simpler 
than the [gets workaround] from RS, because GUI-elements in a text-environment look somewhat strange. - [RS] One should always use [tclsh] these days, and [package require] [Tk] where needed. This way, stdin should remain available...

[HJG] I tried that, but then scripts which use Tk keep their console window - that does not look good.
I cannot get rid of it with "''console hide''", and "''wm withdraw .''" hides the Tk-window.
On the page [tclsh vs. wish] I could not find advice about this, and it looks like most scripts
here in the wiki use [wish] without "package require Tk".

[LV] If you are writing a graphical user interface, then don't use gets to
get input from the user - use an [entry] widget or a [text] widget.


A version of HiLo with a full GUI is at [HiLo2], 
and an international version at [HiLo-international]
----
!!!!!!
%| [Category Games] |%
!!!!!!