Guess the number/With feedback (player)

Revision as of 23:17, 8 January 2022 by ReeceGoding (talk | contribs) (→‎{{header|R}}: Syntax highlighting.)

Write a player for the game that follows the following rules:

Task
Guess the number/With feedback (player)
You are encouraged to solve this task according to the task description, using any language you may know.
Task
The scorer will choose a number between set limits. The computer player will print a guess of the target number. The computer asks for a score of whether its guess is higher than, lower than, or equal to the target. The computer guesses, and the scorer scores, in turn, until the computer correctly guesses the target number.

The computer should guess intelligently based on the accumulated scores given. One way is to use a Binary search based algorithm.


Related tasks



11l

Translation of: Python

<lang 11l>V (target_min, target_max) = (1, 10) V (mn, mx) = (target_min, target_max)

print( ‘Think of a number between #. and #. and wait for me to guess it. On every guess of mine you should state whether the guess was too high, too low, or equal to your number by typing h, l, or = ’.format(target_min, target_max))

V i = 0 L

  i++
  V guess = (mn + mx) I/ 2
  V txt = input(‘Guess #2 is: #2. The score for which is (h,l,=): ’.format(i, guess)).trim(‘ ’).lowercase()[0]
  I txt !C ‘hl=’
     print(‘  I don't understand your input of '#.' ?’.format(txt))
     L.continue
  I txt == ‘h’
     mx = guess - 1
  I txt == ‘l’
     mn = guess + 1
  I txt == ‘=’
     print(‘  Ye-Haw!!’)
     L.break
  I (mn > mx) | (mn < target_min) | (mx > target_max)
     print(‘Please check your scoring as I cannot find the value’)
     L.break

print("\nThanks for keeping score.")</lang>

Output:
Think of a number between 1 and 10 and wait for me to guess it.
On every guess of mine you should state whether the guess was
too high, too low, or equal to your number by typing h, l, or =

Guess  1 is:  5. The score for which is (h,l,=): l
Guess  2 is:  8. The score for which is (h,l,=): l
Guess  3 is:  9. The score for which is (h,l,=): l
Guess  4 is: 10. The score for which is (h,l,=): =
  Ye-Haw!!

Thanks for keeping score.

Action!

<lang Action!>PROC Main()

 BYTE n,min=[1],max=[100]
 CHAR c
 PrintF("Think a number in range %B-%B%E",min,max)
 DO
   n=(max+min) RSH 1
   PrintF("My guess is %B%E",n)
   PrintF("Is it (E)qual, (L)ower or (H)igher?")
   c=GetD(7)
   Put(c) PutE()
   IF c='E THEN
     Print("I guessed!")
     EXIT
   ELSEIF c='L THEN
     max=n-1
   ELSEIF c='H THEN
     min=n+1
   FI
   IF max<min THEN
     Print("You are cheating...")
     EXIT
   FI
 OD

RETURN</lang>

Output:

Screenshot from Atari 8-bit computer

Think a number in range 1-100
My guess is 50
Is it (E)qual, (L)ower or (H)igher?L
My guess is 25
Is it (E)qual, (L)ower or (H)igher?L
My guess is 12
Is it (E)qual, (L)ower or (H)igher?H
My guess is 18
Is it (E)qual, (L)ower or (H)igher?L
My guess is 15
Is it (E)qual, (L)ower or (H)igher?L
My guess is 13
Is it (E)qual, (L)ower or (H)igher?E
I guessed!

Ada

<lang Ada>with Ada.Text_IO; procedure Guess_Number_Player is

  procedure Guess_Number (Lower_Limit : Integer; Upper_Limit : Integer) is
     type Feedback is (Lower, Higher, Correct);
     package Feedback_IO is new Ada.Text_IO.Enumeration_IO (Feedback);
     My_Guess : Integer := Lower_Limit + (Upper_Limit - Lower_Limit) / 2;
     Your_Feedback : Feedback;
  begin
     Ada.Text_IO.Put_Line ("Think of a number!");
     loop
        Ada.Text_IO.Put_Line ("My guess: " & Integer'Image (My_Guess));
        Ada.Text_IO.Put ("Your answer (lower, higher, correct): ");
        Feedback_IO.Get (Your_Feedback);
        exit when Your_Feedback = Correct;
        if Your_Feedback = Lower then
           My_Guess := Lower_Limit + (My_Guess - Lower_Limit) / 2;
        else
           My_Guess := My_Guess + (Upper_Limit - My_Guess) / 2;
        end if;
     end loop;
     Ada.Text_IO.Put_Line ("I guessed well!");
  end Guess_Number;
  package Int_IO is new Ada.Text_IO.Integer_IO (Integer);
  Lower_Limit : Integer;
  Upper_Limit : Integer;

begin

  loop
     Ada.Text_IO.Put ("Lower Limit: ");
     Int_IO.Get (Lower_Limit);
     Ada.Text_IO.Put ("Upper Limit: ");
     Int_IO.Get (Upper_Limit);
     exit when Lower_Limit < Upper_Limit;
     Ada.Text_IO.Put_Line ("Lower limit must be lower!");
  end loop;
  Guess_Number (Lower_Limit, Upper_Limit);

end Guess_Number_Player;</lang>

ALGOL 68

Works with: ALGOL 68G version Any - tested with release 2.8.3.win32

<lang algol68>BEGIN

   INT    lower    :=    1;
   INT    upper    :=  100;
   print( ( "Think of a number between ", whole( lower, 0 ), " and ", whole( upper, 0 ), newline ) );
   print( ( "Please enter Y if I guess correctly, L is it is lower, G if it is greater or Q if you've had enough", newline ) );
   WHILE
       INT mid = lower + ( ( upper - lower ) OVER 2 );
       CHAR reply;
       WHILE
           print( ( "Is it ", whole( mid, 0 ), "?    Y/L/G/Q: " ) );
           read( ( reply, newline ) );
           NOT char in string( reply, NIL, "YLGQylgq" )
       DO SKIP OD;
       IF   reply = "Q" OR reply = "q" OR reply = "Y" OR reply = "y"
       THEN FALSE
       ELIF lower >= upper THEN
           print( ( "Based on your answers so far, it must be ", whole( lower, 0 ), newline ) );
           FALSE
       ELSE
           IF   reply = "L" OR reply = "l" THEN upper := mid - 1
           ELIF reply = "G" OR reply = "g" THEN lower := mid + 1
           FI;
           TRUE
       FI
   DO SKIP OD

END</lang>

AppleScript

<lang AppleScript>-- defining the range of the number to be guessed property minLimit : 1 property maxLimit : 100

on run -- ask the user to think of a number in the given range display dialog "Please think of a number between " & minLimit & " and " & maxLimit

-- prepare a variable for the lowest guessed value set lowGuess to minLimit -- prepare a variable for the highest guessed value set highGuess to maxLimit

repeat -- guess a number inside the logical range set computersGuess to (random number from lowGuess to highGuess) -- ask the user to check my guess set guessResult to button returned of (display dialog "I guess " & computersGuess & "!" & return & "What do you think?" buttons {"Lower", "Correct", "Higher"}) if guessResult = "Lower" then -- the number is less than the guess, switch the upper limit to the guess set highGuess to computersGuess else if guessResult = "Higher" then -- the number is greater than the guess, switch the lower limit to the guess set lowGuess to computersGuess else if guessResult = "Correct" then -- the computer guessed the number, beep and exit beep exit repeat end if end repeat end run</lang>

AutoHotkey

Works with the AutoHotkey entry at: Guess the number/With feedback

<lang AutoHotkey>MaxGuesses = 50

GetParams(LowerBound,UpperBound) If Not GuessNum(LowerBound,UpperBound,MaxGuesses)

MsgBox, 16, Error, Could not guess number within %MaxGuesses% guesses.

GetParams(ByRef LowerBound,ByRef UpperBound) {

WinWait, Number Guessing ahk_class #32770
Sleep, 100
WinGet, InputID, ID
ControlGetText, Temp1, Static1, ahk_id %InputID%
Temp2 := InStr(Temp1,A_Space,False,32)
LowerBound := SubStr(Temp1,31,Temp2 - 31)
UpperBound := SubStr(Temp1,Temp2 + 5,-1)

}

GuessNum(LowerBound,UpperBound,MaxGuesses) {

Loop, %MaxGuesses%
{
 Guess := LowerBound + ((UpperBound - LowerBound) // 2)
 Temp1 := SendGuess(Guess)
 ToolTip % Temp1
 If Temp1 = Too Low
  LowerBound = %Guess%
 Else If Temp1 = Too High
  UpperBound = %Guess%
 Else
  Return, 1
}

}

SendGuess(Guess) {

WinGet, InputID, ID, Number Guessing ahk_class #32770
ControlSetText, Edit1, %Guess%, ahk_id %InputID%
ControlSend, Button1, {Enter}, ahk_id %InputID%
Loop
{
 Sleep, 50
 IfWinExist, Correct ahk_class #32770
  Return
 Else IfWinExist, Incorrect ahk_class #32770
  Break
}
ControlGetText, Temp1, Static2
WinClose
WinWaitClose
IfInString, Temp1, low
 Return, "Too Low"
Else
 Return, "Too High"

}</lang>

Batch File

<lang dos> @echo off

Player is prompted to give a number between %min% and %max%. If the input is out of those limits they are prompted to choose again
choose

set min=0 set max=100

set /p "number=Choose a number [%min%-%max%]: " if %number% gtr %max% goto choose if %number% lss %min% goto choose set attempts=0

Loops the guessing process until completed
comp

set /a attempts+=1 set /a guess=(%max%-%min%)/2+%min% choice /c "HLE" /n /m "Guess: %guess% - [H]igher, [L]ower or [E]qual" if errorlevel 3 goto end if errorlevel 2 (

 set max=%guess%
 goto comp

) if errorlevel 1 (

 set min=%guess%
 goto comp

)

end

echo Guesses: %attempts% pause>nul </lang>

Output:
Choose a number [0-100]: 42
Guess: 50 - [H]igher, [L]ower or [E]qual L
Guess: 25 - [H]igher, [L]ower or [E]qual H
Guess: 37 - [H]igher, [L]ower or [E]qual H
Guess: 43 - [H]igher, [L]ower or [E]qual L
Guess: 40 - [H]igher, [L]ower or [E]qual H
Guess: 41 - [H]igher, [L]ower or [E]qual H
Guess: 42 - [H]igher, [L]ower or [E]qual E
Guesses: 7

BASIC

<lang basic>10 DEFINT A-Z 20 INPUT "Lower limit? ",L 30 INPUT "Upper limit? ",H 40 IF L>H THEN PRINT "Invalid input": END 50 PRINT "My guess is ";(H-L)\2+L 55 T=T+1 60 INPUT "Too low (L), too high (H), or correct (C)? ",R$ 70 ON INSTR("LlHhCc",R$) GOTO 90,90,100,100,110,110 80 PRINT "Invalid input": GOTO 50 90 L=(H-L)\2+L: GOTO 40 100 H=(H-L)\2+L: GOTO 40 110 PRINT "It took";T;"tries."</lang>

Output:
Lower limit? 1
Upper limit? 100
My guess is  50
Too low (L), too high (H), or correct (C)? L
My guess is  75
Too low (L), too high (H), or correct (C)? L
My guess is  87
Too low (L), too high (H), or correct (C)? H
My guess is  81
Too low (L), too high (H), or correct (C)? L
My guess is  84
Too low (L), too high (H), or correct (C)? L
My guess is  85
Too low (L), too high (H), or correct (C)? C
It took 6 tries.

BBC BASIC

<lang bbcbasic> min% = 1

     max% = 100
     PRINT "Think of a number between "; min% " and " ;max%
     PRINT "I will try to guess your number."
     REPEAT
       guess% = (min% + max%) DIV 2
       PRINT "My guess is " ; guess%
       INPUT "Is it higher than, lower than or equal to your number", answer$
       CASE LEFT$(answer$,1) OF
         WHEN "L","l": min% = guess% + 1
         WHEN "H","h": max% = guess% - 1
         WHEN "E","e": EXIT REPEAT
         OTHERWISE: PRINT "Sorry, I didn't understand your answer."
       ENDCASE
     UNTIL FALSE
     PRINT "Goodbye."
     END</lang>

BCPL

<lang bcpl>get "libhdr"

let reads(s) = valof $( s%0 := 0

   $(  let c = rdch()
       if c = endstreamch resultis false
       if c = '*N' resultis true
       s%0 := s%0 + 1
       s%(s%0) := c
   $) repeat 

$)

let choose(chs) = valof $( let ans = vec 80

   writef("[%S]? ",chs)
   unless reads(ans) finish
   unless ans%0=1 loop
   for i=1 to chs%0
       if (ans%1|32) = (chs%i|32) resultis chs%i

$) repeat

let tantrum() be $( writes("Cheater!*N")

   finish

$)

let guess(lo, hi, t) = valof $( let ans = vec 80

   test hi<lo do tantrum()
   or test hi=lo
   $(  writef("Is the number %N ",lo)
       test choose("yn")='y' resultis t or tantrum()
   $)
   or
   $(  let g = (hi-lo)/2+lo 
       writef("My guess is %N. Too low, too high, or correct ",g)
       switchon choose("lhc") into
       $(  case 'l': resultis guess(g, hi, t+1)
           case 'h': resultis guess(lo, g, t+1)
           case 'c': resultis t
       $)
   $)

$)

let start() be $( let min = ? and max = ?

   writes("Lower bound? ") ; min := readn()
   writes("Upper bound? ") ; max := readn()
   writef("It took %N attempts.*N", guess(min, max, 1))

$)</lang>

Output:
Lower bound? 1
Upper bound? 100
My guess is 50. Too low, too high, or correct [lhc]? l
My guess is 75. Too low, too high, or correct [lhc]? l
My guess is 87. Too low, too high, or correct [lhc]? h
My guess is 81. Too low, too high, or correct [lhc]? l
My guess is 84. Too low, too high, or correct [lhc]? l
My guess is 85. Too low, too high, or correct [lhc]? c
It took 6 attempts.

C

<lang C>#include <stdio.h>

int main(){

 int bounds[ 2 ] = {1, 100};
 char input[ 2 ] = "  ";
   /* second char is for the newline from hitting [return] */
 int choice = (bounds[ 0 ] + bounds[ 1 ]) / 2;
   /* using a binary search */
 printf( "Choose a number between %d and %d.\n", bounds[ 0 ], bounds[ 1 ] );
 do{
   switch( input[ 0 ] ){
     case 'H':
       bounds[ 1 ] = choice;
       break;
     case 'L':
       bounds[ 0 ] = choice;
       break;
     case 'Y':
       printf( "\nAwwwright\n" );
       return 0;
   }
   choice = (bounds[ 0 ] + bounds[ 1 ]) / 2;
   printf( "Is the number %d? (Y/H/L) ", choice );
 }while( scanf( "%1s", input ) == 1 );
 return 0;

}</lang>

Demonstration (number is 57):

Choose a number between 1 and 100.
Is the number 50? (Y/H/L) L
Is the number 75? (Y/H/L) H
Is the number 62? (Y/H/L) H
Is the number 56? (Y/H/L) L
Is the number 59? (Y/H/L) H
Is the number 57? (Y/H/L) Y

Awwwright

The following is a hacky solution using bsearch() and pointers to represent integers. Although the pointers do not point to valid things, bsearch() doesn't actually dereference the pointers or care what they point to; it just passes them to the comparator and searches the space of pointers. We can use that to search any space of integers.

Translation of: Java

<lang c>#include <stdio.h>

  1. include <stdlib.h>
  2. include <ctype.h>

enum {

 LOWER = 0,
 UPPER = 100,
 KEY = LOWER-1 // some value that is not in the valid range

};

char dummy; // A pointer to represent the integer 0, and the basis of our integer-as-pointer // representation. We can't use the null pointer because bsearch() returns that // for not found.

  1. define ZERO ((void *)&dummy)

int get_value(int x) {

 if (x == KEY)
   return 0;
 printf("My guess is: %d. Is it too high, too low, or correct? (H/L/C) ", x);
 char input[2] = " ";
 scanf("%1s", input);
 switch (tolower(input[0])) {
   case 'l':
     return -1;
   case 'h':
     return 1;
   case 'c':
     return 0;
 }
 fprintf(stderr, "Invalid input\n");
 exit(1);
 return 0;

}

int my_cmp(const void *x, const void *y) {

 return get_value(x - ZERO) - get_value(y - ZERO);

}

int main() {

 printf("Instructions:\n"

"Think of integer number from %d (inclusive) to %d (exclusive) and\n" "I will guess it. After each guess, you respond with L, H, or C depending\n" "on if my guess was too low, too high, or correct.\n", LOWER, UPPER);

 void *result = bsearch(ZERO + KEY, ZERO + LOWER, UPPER-LOWER, 1, my_cmp);
 if (result == NULL)
   fprintf(stderr, "That is impossible.\n");
 else
   printf("Your number is %d.\n", (int)(result - ZERO));
 return 0;

}</lang>

C#

<lang csharp>using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Threading; //Remember to add this if you want the game to pause in RealisticGuess.Start()

namespace ConsoleApplication1 {

   class RealisticGuess //Simulates a guessing game between two people. Guessing efficiency is not a goal.
   {
       private int max;
       private int min;
       private int guess;
       public void Start()
       {
           Console.Clear();
           string input;
           try
           {
               Console.WriteLine("Please enter the lower boundary");
               input = Console.ReadLine();
               min = Convert.ToInt32(input);
               Console.WriteLine("Please enter the upper boundary");
               input = Console.ReadLine();
               max = Convert.ToInt32(input);
           }
           catch (FormatException)
           {
               Console.WriteLine("The entry you have made is invalid. Please make sure your entry is an integer and try again.");
               Console.ReadKey(true);
               Start();
           }
           Console.WriteLine("Think of a number between {0} and {1}.", min, max);
           Thread.Sleep(2500);
           Console.WriteLine("Ready?");
           Console.WriteLine("Press any key to begin.");
           Console.ReadKey(true);
           Guess(min, max);
       }
       public void Guess(int min, int max)
       {
           int counter = 1;
           string userAnswer;
           bool correct = false;
           Random rand = new Random();
           while (correct == false)
           {
               guess = rand.Next(min, max);
               Console.Clear();
               Console.WriteLine("{0}", guess);
               Console.WriteLine("Is this number correct? {Y/N}");
               userAnswer = Console.ReadLine();
               if (userAnswer != "y" && userAnswer != "Y" && userAnswer != "n" && userAnswer != "N")
               {
                   Console.WriteLine("Your entry is invalid. Please enter either 'Y' or 'N'");
                   Console.WriteLine("Is the number correct? {Y/N}");
                   userAnswer = Console.ReadLine();
               }
               if (userAnswer == "y" || userAnswer == "Y")
               {
                   correct = true;
               }
               if (userAnswer == "n" || userAnswer == "N")
               {
                   counter++;
                   if (max == min)
                   {
                       Console.WriteLine("Error: Range Intersect. Press enter to restart the game.");  //This message should never pop up if the user enters good data.
                       Console.ReadKey(true);                                                          //It handles the game-breaking exception that occurs
                       Guess(1, 101);                                                                  //when the max guess number is the same as the min number.
                   }
                   Console.WriteLine("Is the number you're thinking of lower or higher? {L/H}");
                   userAnswer = Console.ReadLine();
                   if (userAnswer != "l" && userAnswer != "L" && userAnswer != "h" && userAnswer != "H")
                   {
                       Console.WriteLine("Your entry is invalid. Please enter either 'L' or 'H'");
                       Console.WriteLine("Is the number you're thinking of lower or higher? {L/H}");
                       userAnswer = Console.ReadLine();
                   }
                   if (userAnswer == "l" || userAnswer == "L")
                   {
                       max = guess;
                   }
                   if (userAnswer == "h" || userAnswer == "H")
                   {
                       min = guess;
                   }
               }
           }
           if (correct == true)
           {
               EndAndLoop(counter);
           }
       }
       public void EndAndLoop(int iterations)
       {
           string userChoice;
           bool loop = false;
           Console.WriteLine("Game over. It took {0} guesses to find the number.", iterations);
           while (loop == false)
           {
               Console.WriteLine("Would you like to play again? {Y/N}");
               userChoice = Console.ReadLine();
               if (userChoice != "Y" && userChoice != "y" && userChoice != "N" && userChoice != "n")
               {
                   Console.WriteLine("Sorry, your input is invalid. Please answer 'Y' to play again, or 'N' to quit.");
               }
               if (userChoice == "Y" || userChoice == "y")
               {
                   Start();
               }
               if (userChoice == "N" || userChoice == "n")
               {
                   Environment.Exit(1);
               }
           }
       }
   }
   class Program
   {
       static void Main(string[] args)
       {
           Console.Title = "Random Number";
           RealisticGuess game = new RealisticGuess();
           game.Start();
       }
   }

} </lang>

C++

A clever solution that takes advantage of C++'s built-in binary search function lower_bound(). Instead of searching a slice of a container, we search a range of numbers by implementing a specially-designed custom iterator.

Translation of: Go

<lang cpp>#include <iostream>

  1. include <algorithm>
  2. include <string>
  3. include <iterator>

struct GuessNumberIterator : std::iterator<std::random_access_iterator_tag, int> {

 int i;
 GuessNumberIterator() { }
 GuessNumberIterator(int _i) : i(_i) { }
 GuessNumberIterator& operator++() { ++i; return *this; }
 GuessNumberIterator operator++(int) {
   GuessNumberIterator tmp = *this; ++(*this); return tmp; }
 bool operator==(const GuessNumberIterator& y) { return i == y.i; }
 bool operator!=(const GuessNumberIterator& y) { return i != y.i; }
 int operator*() {
   std::cout << "Is your number less than or equal to " << i << "? ";
   std::string s;
   std::cin >> s;
   return (s != "" && (s[0] == 'y' || s[0] == 'Y')) ? 0 : -1;
 }
 GuessNumberIterator& operator--() { --i; return *this; }
 GuessNumberIterator operator--(int) {
   GuessNumberIterator tmp = *this; --(*this); return tmp; }
 GuessNumberIterator& operator+=(int n) { i += n; return *this; }
 GuessNumberIterator& operator-=(int n) { i -= n; return *this; }
 GuessNumberIterator operator+(int n) {
   GuessNumberIterator tmp = *this; return tmp += n; }
 GuessNumberIterator operator-(int n) {
   GuessNumberIterator tmp = *this; return tmp -= n; }
 int operator-(const GuessNumberIterator &y) { return i - y.i; }
 int operator[](int n) { return *(*this + n); }
 bool operator<(const GuessNumberIterator &y) { return i < y.i; }
 bool operator>(const GuessNumberIterator &y) { return i > y.i; }
 bool operator<=(const GuessNumberIterator &y) { return i <= y.i; }
 bool operator>=(const GuessNumberIterator &y) { return i >= y.i; }

}; inline GuessNumberIterator operator+(int n, GuessNumberIterator &i) { return i + n; }

const int lower = 0; const int upper = 100;

int main() {

 std::cout << "Instructions:\n"

<< "Think of integer number from " << lower << " (inclusive) to " << upper << " (exclusive) and\n" << "I will guess it. After each guess, I will ask you if it is less than\n" << "or equal to some number, and you will respond with \"yes\" or \"no\".\n";

 int answer = std::lower_bound(GuessNumberIterator(lower), GuessNumberIterator(upper), 0).i;
 std::cout << "Your number is " << answer << ".\n";
 return 0;

}</lang>

Ceylon

<lang ceylon>shared void run() {

   while(true) {
       variable value low = 1;
       variable value high = 10;
       variable value attempts = 1;
       print("Please choose a number between ``low`` and ``high``.
              Press enter when ready.");
       process.readLine();
       while(true) {
           if(low > high) {
               print("Something is wrong. I give up.");
               break;
           }
           variable value guess = (low + high) / 2;
           print("Is ``guess`` (e)qual, (h)igher or (l)ower to your number?
                  (enter q to quit)");
           value answer = process.readLine()?.trimmed?.lowercased;
           switch(answer)
           case("e") {
               print("I got it in only ``attempts`` ``attempts == 1 then "try" else "tries"``!");
               break;
           }
           case("h") {
               high = guess - 1;
               attempts++;
           }
           case("l") {
               low = guess + 1;
               attempts++;
           }
           case("q") {
               return;
           }
           else {
               print("Please enter an e, h, l or q");
           }
       }
   }

}</lang>

Clojure

<lang Clojure>(require '[clojure.string :as str])

(defn guess-game [low high]

 (printf "Think of a number between %s and %s.\n (use (h)igh (l)ow (c)orrect)\n" low high)
 (loop [guess (/ (inc (- high low)) 2)
        [step & more] (next (iterate #(/ % 2) guess))]
   (printf "I guess %s\n=> " (Math/round (float guess)))
   (flush)
   (case (first (str/lower-case (read)))
     \h (recur (- guess step) more)
     \l (recur (+ guess step) more)
     \c (println "Huzzah!")
     (do (println "Invalid input.")
         (recur guess step)))))</lang>

Output

user=> (guess-game 1 100)
Think of a number between 1 and 100.
 (use (h)igh (l)ow (c)orrect)
I guess 50
=> l
I guess 63
=> h
I guess 56
=> l
I guess 59
=> l
I guess 61
=> c
Huzzah!

Common Lisp

An imperative solution using LOOP: <lang Lisp> (defun guess-the-number (&optional (max 1000) (min 0))

 (flet ((get-feedback (guess)
          (loop
             initially (format t "I choose ~a.~%" guess)
             for answer = (read)
             if (member answer '(greater lower correct))
             return answer
             else do (write-line "Answer greater, lower, or correct."))))
   (loop
      initially (format t "Think of a number between ~a and ~a.~%" min max)
      for guess  = (floor (+ min max) 2)
      for answer = (get-feedback guess)
      until (eq answer 'correct)
      if (eq answer 'greater) do (setf min guess)
      else do (setf max guess)
      finally (write-line "I got it!"))))

</lang>

A recursive solution (we use LABELS instead of FLET for the local function definitions in this version so that GUESS-LOOP will be able to call itself recursively): <lang Lisp> (defun guess-the-number (&optional (max 1000) (min 0))

 (labels ((guess-loop (min max)
            (let ((guess (floor (+ min max) 2)))
              (format t "I choose ~a.~%" guess)
              (case (read)
                (greater (guess-loop guess max))
                (lower   (guess-loop min guess))
                (correct (write-line "I got it!"))
                (otherwise
                  (write-line "Please answer greater, lower, or correct.")
                  (guess-loop min max))))))
   (format t "Think of a number between ~a and ~a.~%" min max)
   (guess-loop min max)))

</lang>

D

Translation of: Python

<lang d>import std.stdio, std.string;

void main() {

   immutable mnOrig = 1, mxOrig = 10;
   int mn = mnOrig, mx = mxOrig;
   writefln(
   "Think of a number between %d and %d and wait for me to guess it.
   On every guess of mine you should state whether the guess was
   too high, too low, or equal to your number by typing h, l, or =",
           mn, mx);
   LOOP: for (int i = 1; ; i++) {
       immutable guess = (mn + mx) / 2;
       writef("Guess %2d is: %2d. The score for which is (h,l,=): ",
              i, guess);
       immutable string txt = readln().strip().toLower();
       switch (txt) {
           case "h":
               mx = guess - 1;
               break;
           case "l":
               mn = guess + 1;
               break;
           case "=":
               writeln("  Yeehaw!!");
               break LOOP;
           default:
               writefln("  I don't understand your input '%s'.",
                        txt);
               continue LOOP;
       }
       if (mn > mx || mn < mnOrig || mx > mxOrig) {
           writeln("Please check your scoring as" ~
                   " I cannot find the value");
           break;
       }
   }
   writeln("\nThanks for keeping score.");

}</lang>

Output:
Think of a number between 1 and 10 and wait for me to guess it.
    On every guess of mine you should state whether the guess was
    too high, too low, or equal to your number by typing h, l, or =
Guess  1 is:  5. The score for which is (h,l,=): l
Guess  2 is:  8. The score for which is (h,l,=): h
Guess  3 is:  6. The score for which is (h,l,=): l
Guess  4 is:  7. The score for which is (h,l,=): =
  Yeehaw!!

Thanks for keeping score.

Delphi

Thanks JensBorrisholt for System.Console [1]. <lang Delphi> program Guess_the_number;

{$APPTYPE CONSOLE}

uses

 System.SysUtils,
 system.console;

type

 TCharSet = set of char;

var

 PlayerNumber, CPUNumber: word;
 CPULow: word = 0;
 CPUHi: word = 1000;
 PlayerLow: word = 0;
 PlayerHi: word = 1000;
 CPUWin, PlayerWin: boolean;
 CPUGuessList: string = 'Previus guesses:'#10;
 PlayerGuessList: string = 'Previus guesses:'#10;

function WaitKey(validSet: TCharSet): char; begin

 repeat
   Result := Console.ReadKey.KeyChar;
 until (Result in validSet);

end;

function QueryNumber(msg: string): Integer; var

 buf: string;

begin

 repeat
   Console.WriteLine(msg);
   buf := Console.ReadLine.Replace(#10, ).Replace(#13, );
 until TryStrToInt(buf, result);

end;

procedure Wait; begin

 Console.ForegroundColor := TConsoleColor.Yellow;
 Console.WriteLine(#10'Press Enter to continue');
 WaitKey([#13]);
 Console.ForegroundColor := TConsoleColor.White;

end;

function PlayLuck: integer; var

 cpu, player: double;

begin

 cpu := CPUHi - CPULow + 1;
 player := PlayerHi - PlayerLow + 1;
 Result := round(100 * cpu / (cpu + player));

end;

function PlayerTurn: boolean; var

 guess: word;

begin

 Console.Clear;
 Console.WriteLine('Player Turn({0}%%):'#10, [PlayLuck]);
 Console.ForegroundColor := TConsoleColor.Gray;
 console.WriteLine(PlayerGuessList + #10);
 console.WriteLine(#10 + 'Tip: {0}..{1}' + #10, [PlayerLow, PlayerHi]);
 Console.ForegroundColor := TConsoleColor.Red;
 guess := QueryNumber('Enter your guess number:');
 Console.ForegroundColor := TConsoleColor.White;
 if guess > CPUNumber then
 begin
   Console.WriteLine('{0} is to high', [guess]);
   PlayerGuessList := PlayerGuessList + '   ' + guess.tostring + ' is to high'#10;
   PlayerHi := guess - 1;
 end;
 if guess < CPUNumber then
 begin
   Console.WriteLine('{0} is to Low', [guess]);
   PlayerGuessList := PlayerGuessList + '   ' + guess.tostring + ' is to low'#10;
   PlayerLow := guess + 1;
 end;
 Result := guess = CPUNumber;
 if Result then
   Console.WriteLine('Your guess is correct, you rock!')
 else
   Wait;

end;

function CPUTurn: boolean; var

 guess: word;
 ans: char;

begin

 guess := ((CPUHi - CPULow) div 2) + CPULow;
 Console.Clear;
 Console.WriteLine('CPU Turn({0}%%):'#10, [100 - PlayLuck]);
 Console.ForegroundColor := TConsoleColor.Gray;
 console.WriteLine(CPUGuessList + #10);
 console.WriteLine(#10 + 'Tip: {0}..{1}' + #10, [CPULow, CPUHi]);
 Console.ForegroundColor := TConsoleColor.Red;
 Console.WriteLine('My guess number is {0}'#10, [guess]);
 Console.ForegroundColor := TConsoleColor.White;
 Console.WriteLine('Press "l" = too low, "h" = too high, "c" = correct', [guess]);
 ans := WaitKey(['l', 'h', 'c']);
 Result := false;
 case ans of
   'l':
     begin
       CPULow := guess + 1;
       Console.WriteLine(#10'Then my guess is to low'#10);
       CPUGuessList := CPUGuessList + '   ' + guess.tostring + ' is to low'#10;
     end;
   'h':
     begin
       CPUHi := guess - 1;
       Console.WriteLine(#10'Then my guess is to high'#10);
       CPUGuessList := CPUGuessList + '   ' + guess.tostring + ' is to high'#10;
     end
 else
   Result := True;
 end;
 if Result then
   Console.WriteLine(#10'My guess is correct, Good luck in the next time')
 else
   Wait;

end;

begin

 Randomize;
 CPUNumber := Random(1001);
 Console.WriteLine('Press Enter and I will start to guess the number.');
 repeat
   PlayerWin := PlayerTurn();
   if PlayerWin then
     Break;
   CPUWin := CPUTurn();
   if CPUWin then
     Break;
 until false;
 Console.ForegroundColor := TConsoleColor.Green;
 if PlayerWin then
   Console.WriteLine('Player win!')
 else
 begin
   Console.WriteLine('CPU win!');
   Console.WriteLine('If you wanna know, my number was {0}', [CPUNumber]);
 end;
 readln;

end.</lang>

Elixir

Works with: Elixir version 1.2

<lang Elixir>defmodule Game do

 def guess(a..b) do
   x = Enum.random(a..b)
   guess(x, a..b, div(a+b, 2))
 end
 
 defp guess(x, a.._b, guess) when x < guess do
   IO.puts "Is it #{guess}? Too High."
   guess(x, a..guess-1, div(a+guess, 2))
 end
 defp guess(x, _a..b, guess) when x > guess do
   IO.puts "Is it #{guess}? Too Low."
   guess(x, guess+1..b, div(guess+b+1, 2))
 end
 defp guess(x, _, _) do
   IO.puts "Is it #{x}?"
   IO.puts " So the number is: #{x}"
 end

end Game.guess(1..100)</lang>

sample:
Is it 50? Too High.
Is it 25? Too High.
Is it 13? Too High.
Is it 7? Too Low.
Is it 10?
 So the number is: 10

Erlang

<lang erlang>% Implemented by Arjun Sunel -module(guess_game). -export([main/0]).

main() -> L = 1 , % Lower Limit U = 100,  % Upper Limit

io:fwrite("Player 1 : Guess my number between ~p and ", [L]), io:fwrite("and ~p until you get it right.\n", [U]), N = random:uniform(100), guess(L,U,N).

guess(L,U,N) -> K = (L+U) div 2, io:format("Player 2 : Number guessed : ~p~n",[K]), if K=:=N -> io:format("Well guessed!! by Player 2\n"); true -> if K > N -> io:format("Player 1 : Your guess is too high!\n"), guess(L,K,N); true -> io:format("Player 1 : Your guess is too low!\n"), guess(K,U,N) end end.</lang>

Output:
Player 1 : Guess my number between 1 and and 100 until you get it right.
Player 2 : Number guessed : 50
Player 1 : Your guess is too high!
Player 2 : Number guessed : 25
Player 1 : Your guess is too high!
Player 2 : Number guessed : 13
Player 1 : Your guess is too high!
Player 2 : Number guessed : 7
Player 1 : Your guess is too low!
Player 2 : Number guessed : 10
Well guessed!! by Player 2
ok

Euphoria

Translation of: PureBasic

<lang euphoria>include get.e include wildcard.e

sequence Respons integer min, max, Guess min = 0 max = 100

printf(1,"Think of a number between %d and %d.\n",{min,max}) puts(1,"On every guess of mine you should state whether my guess was\n") puts(1,"too high, too low, or equal to your number by typing 'h', 'l', or '='\n")

while 1 do

   if max < min then
       puts(1,"I think something is strange here...\n")
       exit
   end if
   Guess = floor((max-min)/2+min)
   printf(1,"My guess is %d, is this correct? ", Guess)
   Respons = upper(prompt_string(""))
   if Respons[1] = 'H' then
       max = Guess-1
   elsif Respons[1] = 'L' then
       min = Guess+1
   elsif Respons[1] = '=' then
       puts(1,"I did it!\n")
       exit
   else
       puts(1,"I do not understand that...\n")
   end if

end while</lang>

Factor

This solution uses the search combinator. It performs a binary search on a sequence by placing the "guess" on top of the data stack and expecting an ordering specifier in return. <lang factor>USING: binary-search formatting io kernel math.ranges words ;

instruct ( -- )
   "Think of a number between 1 and 100." print
   "Score my guess with +lt+ +gt+ or +eq+." print nl ;
score ( n -- <=> )
   "My guess is %d. " printf readln "math.order" lookup-word ;
play-game ( -- n )
   100 [1,b] [ score ] search nip nl ;
gloat ( n -- )
   "I did it. Your number was %d!\n" printf ;

instruct play-game gloat</lang>

Output:
Think of a number between 1 and 100.
Score my guess with +lt+ +gt+ or +eq+.

My guess is 51. +lt+
My guess is 26. +gt+
My guess is 38. +lt+
My guess is 32. +gt+
My guess is 35. +lt+
My guess is 33. +eq+

I did it. Your number was 33!

Fantom

<lang fantom> class Main {

 public static Void main ()
 {
   Int lowerLimit := 1
   Int higherLimit := 100
   echo ("Think of a number between 1 and 100")
   echo ("Press 'enter' when ready")
   Env.cur.in.readLine
   
   while (true)
   {
     if (higherLimit < lowerLimit)
     { // check that player is not cheating!
       echo ("Something has gone wrong ... I give up")
       break
     }
     myGuess := (higherLimit + lowerLimit) / 2
     echo ("My guess is $myGuess")
     echo ("Enter 'H' if your number is higher, 'L' if lower, or 'E' if equal")
     switch (Env.cur.in.readLine.trim.upper)
     {
       case "E": 
         echo ("I got it correct - thankyou!")
         break // game over
       case "H": 
         lowerLimit = myGuess + 1
       case "L":
         higherLimit = myGuess - 1
       default:
         echo ("Pardon? Let's try that again")
     }
   }
 }

} </lang>

Example:

Think of a number between 1 and 100
Press 'enter' when ready

My guess is 50
Enter 'H' if your number is higher, 'L' if lower, or 'E' if equal
a
Pardon? Let's try that again
My guess is 50
Enter 'H' if your number is higher, 'L' if lower, or 'E' if equal
l
My guess is 25
Enter 'H' if your number is higher, 'L' if lower, or 'E' if equal
h
My guess is 37
Enter 'H' if your number is higher, 'L' if lower, or 'E' if equal
h
My guess is 43
Enter 'H' if your number is higher, 'L' if lower, or 'E' if equal
h
My guess is 46
Enter 'H' if your number is higher, 'L' if lower, or 'E' if equal
h
My guess is 48
Enter 'H' if your number is higher, 'L' if lower, or 'E' if equal
l
My guess is 47
Enter 'H' if your number is higher, 'L' if lower, or 'E' if equal
e
I got it correct - thankyou!

FOCAL

<lang focal>01.10 A "LOWER LIMIT",L 01.15 A "UPPER LIMIT",H 01.20 S T=0 01.25 I (L-H)1.3;T "INVALID INPUT"!;Q 01.30 S G=FITR((H-L)/2+L) 01.35 T "MY GUESS IS",%4,G,! 01.37 S T=T+1 01.40 A "TOO (L)OW, TOO (H)IGH, OR (C)ORRECT",R 01.45 I (R-0L)1.5,1.65,1.5 01.50 I (R-0H)1.55,1.7,1.55 01.55 I (R-0C)1.6,1.75,1.6 01.60 T "INVALID INPUT"!;G 1.3 01.65 S L=G;G 1.3 01.70 S H=G;G 1.3 01.75 T "ATTEMPTS",T,! 01.80 Q</lang>

Output:
LOWER LIMIT:1
UPPER LIMIT:100
MY GUESS IS=   50
TOO (L)OW, TOO (H)IGH, OR (C)ORRECT:L
MY GUESS IS=   75
TOO (L)OW, TOO (H)IGH, OR (C)ORRECT:L
MY GUESS IS=   87
TOO (L)OW, TOO (H)IGH, OR (C)ORRECT:H
MY GUESS IS=   81
TOO (L)OW, TOO (H)IGH, OR (C)ORRECT:L
MY GUESS IS=   84
TOO (L)OW, TOO (H)IGH, OR (C)ORRECT:L
MY GUESS IS=   85
TOO (L)OW, TOO (H)IGH, OR (C)ORRECT:C
ATTEMPTS=    6

Fortran

Works with: Fortran version 95 and later

<lang fortran>program Guess_a_number_Player

 implicit none
 
 integer, parameter :: limit = 100
 integer :: guess, mx = limit, mn = 1
 real :: rnum
 character(1) :: score
 
 write(*, "(a, i0, a)") "Think of a number between 1 and ", limit, &
                        " and I will try to guess it." 
 write(*, "(a)")  "You score my guess by entering: h if my guess is higher than that number"
 write(*, "(a)")  "                                l if my guess is lower than that number"
 write(*, "(a/)") "                                c if my guess is the same as that number"
 call random_seed
 call random_number(rnum)
 guess = rnum * limit + 1
 do
   write(*, "(a, i0, a,)", advance='no') "My quess is: ", guess, "   Score(h, l or c)?: "
   read*, score
   select case(score)
     case("l", "L")
       mn = guess
       guess = (mx-guess+1) / 2 + mn 
       
     case("h", "H")
       mx = guess
       guess = mx - (guess-mn+1) / 2 
     case("c", "C")
       write(*, "(a)") "I solved it!"
       exit
     case default
       write(*, "(a)") "I did not understand that"
   end select
 end do

end program</lang> Output

Think of a number between 1 and 100 and I will try to guess it.
You score my guess by entering: h if my guess is higher than that number
                                l if my guess is lower than that number
                                c if my guess is the same as that number

My guess is: 58   Score(h, l or c)?: h
My guess is: 29   Score(h, l or c)?: l
My guess is: 44   Score(h, l or c)?: l 
My guess is: 51   Score(h, l or c)?: l 
My guess is: 55   Score(h, l or c)?: l 
My guess is: 57   Score(h, l or c)?: c
I solved it!

FreeBASIC

<lang freebasic>' FB 1.05.0 Win64

Dim hle As String Dim lowest As Integer = 1 Dim highest As Integer = 20 Dim guess As Integer = 10 Print "Please choose a number between 1 and 20 but don't tell me what it is yet" Print Do

 Print "My guess is"; guess
 Do
   Input "Is this higher/lower or equal to your chosen number h/l/e : "; hle
   hle = LCase(hle)
   If hle = "l" AndAlso guess = highest Then
     Print "It can't be more than"; highest; ", try again"
     hle = "i"  invalid
   ElseIf hle = "h" AndAlso guess = lowest Then
     Print "It can't be less than"; lowest; ", try again"
     hle = "i"
   End If    
 Loop Until hle = "h" OrElse hle = "l" OrElse hle = "e"
 If hle = "e" Then
   Print "Good, thanks for playing the gaame with me!"
   Exit Do
 ElseIf hle = "h" Then
   If highest > guess - 1 Then highest = guess - 1   
 Else
   If lowest < guess + 1  Then lowest = guess + 1
 End If  
 guess = (lowest + highest)\2  

Loop End</lang>

Sample input/output

Output:
Please choose a number between 1 and 20 but don't tell me what it is yet

My guess is 10
Is this higher/lower or equal to your chosen number h/l/e : ? l
My guess is 15
Is this higher/lower or equal to your chosen number h/l/e : ? h
My guess is 12
Is this higher/lower or equal to your chosen number h/l/e : ? h
My guess is 11
Is this higher/lower or equal to your chosen number h/l/e : ? e
Good, thanks for playing the gaame with me!

Go

Go's binary search function (sort.Search()) is general enough to be able to do this type of task, as mentioned in the documentation for the function itself.[2] <lang go>package main

import (

   "fmt"
   "sort"

)

func main() {

   lower, upper := 0, 100
   fmt.Printf(`Instructions:

Think of integer number from %d (inclusive) to %d (exclusive) and I will guess it. After each guess, I will ask you if it is less than or equal to some number, and you will respond with "yes" or "no". `, lower, upper)

   answer := sort.Search(upper-lower, func (i int) bool {
       fmt.Printf("Is your number less than or equal to %d? ", lower+i)
       s := ""
       fmt.Scanf("%s", &s)
       return s != "" && s[0] == 'y'
   })
   fmt.Printf("Your number is %d.\n", lower+answer)

}</lang>

Manual solution: <lang go>package main

import (

   "bufio"
   "fmt"
   "os"

)

func main() {

   lower, upper := 1, 100
   fmt.Printf(`Instructions:

Think of integer number from %d (inclusive) to %d (inclusive) and I will guess it. After each guess, you respond with l,h,or c depending on if my guess was too low, too high, or correct. Press enter when you are thinking of a number. `, lower, upper)

   in := bufio.NewReader(os.Stdin)
   in.ReadString('\n')
   for {
       guess := (upper+lower)/2
       fmt.Printf("My guess: %d (l/h/c) ", guess)
       s, err := in.ReadString('\n')
       if err != nil {
           fmt.Println("\nSo, bye.")
           return
       }
       switch s {
       case "l\n":
           lower = guess + 1
       case "h\n":
           upper = guess - 1
       case "c\n":
           fmt.Println("I did it. :)")
           return
       default:
           fmt.Println("Please respond by pressing l, h, or c")
       }
   }

}</lang>

Haskell

Explicit version with arbitrary range: <lang Haskell> main :: IO () main = do

   putStrLn "Please enter the range:"
   putStr   "From: "
   from <- getLine
   putStr   "To: "
   to   <- getLine
   case (from, to) of
        (_) | [(from', "")] <- reads from
            , [(to'  , "")] <- reads to
            , from'         < to' -> loop from' to' 
        (_)  -> putStrLn "Invalid input." >> main

loop :: Integer -> Integer -> IO () loop from to = do

   let guess = (to + from) `div` 2
   putStrLn $ "Is it " ++ show guess ++ "? ((l)ower, (c)orrect, (h)igher)"
   answer <- getLine
   case answer of
       "c" -> putStrLn "Awesome!"
       "l" -> loop from  guess
       "h" -> loop guess to
       (_) -> putStrLn "Invalid answer." >> loop from to

</lang>

Short version with set limits: <lang Haskell> main = f 0 100

 where f x y = let g = div (x + y) 2 in
         putStrLn (show g ++ "? (l,h,c)") >>
         getLine >>= \a -> case a of
                             "l" -> f x g
                             "h" -> f g y
                             "c" -> putStrLn "Yay!"

</lang>

Icon and Unicon

Translation of: Fantom

<lang Icon> procedure main ()

 lower_limit := 1
 higher_limit := 100
 
 write ("Think of a number between 1 and 100")
 write ("Press 'enter' when ready")
 read ()
 repeat {
   if (higher_limit < lower_limit) 
     then { # check that player is not cheating!
       write ("Something has gone wrong ... I give up")
       exit ()
     }
   my_guess := (higher_limit + lower_limit) / 2
   write ("My guess is ", my_guess)
   write ("Enter 'H' if your number is higher, 'L' if lower, or 'E' if equal")
   reply := map(trim(read ()))
   case (reply) of {
     "e" : { 
       write ("I got it correct - thankyou!")
       exit () # game over
     }
     "h" : lower_limit := my_guess + 1
     "l" : higher_limit := my_guess - 1
     default : write ("Pardon? Let's try that again")
   }     
 }

end </lang>

IS-BASIC

<lang IS-BASIC>100 PROGRAM "GuessIt.bas" 110 LET N=100 120 TEXT 80 130 PRINT "Choose a number between 1 and;" N:PRINT "I will start guess the number." 140 LET BL=1:LET UL=100:LET NR=0 150 DO 160 LET GUESS=INT((BL+UL)/2):LET NR=NR+1 170 SET #102:INK 3:PRINT :PRINT "My";NR;". guess: ";GUESS:SET #102:INK 1 180 LET ANSWER=QUESTION 190 SELECT CASE ANSWER 200 CASE 1 210 LET UL=GUESS-1 220 CASE 2 230 LET BL=GUESS+1 240 CASE ELSE 250 END SELECT 260 IF BL>UL THEN PRINT "You are cheating!":LET ANSWER=9 270 LOOP UNTIL ANSWER=0 OR ANSWER=9 280 PRINT "So the number is:" GUESS 290 DEF QUESTION 300 PRINT "Your number: 1 - Is lower?; 2 - Is higher?; 0 - Is equal?" 310 DO 320 LET K$=INKEY$ 330 LOOP UNTIL K$>="0" AND K$<="3" 340 LET QUESTION=VAL(K$) 350 END DEF</lang>

J

<lang j>require 'misc' guess=:3 :0

 'lo hi'=.y
 while.lo < hi do.
   smoutput 'guessing a number between ',(":lo),' and ',":hi
   guess=.lo+?hi-lo
   select.{.deb tolower prompt 'is it ',(":guess),'? '
     case.'y'do. smoutput 'Win!' return.
     case.'l'do. lo=.guess+1
     case.'h'do. hi=.guess-1
     case.'q'do. smoutput 'giving up' return.
     case.   do. smouput 'options: yes, low, high, quit'
   end.
 end.

)</lang>

Example session:

<lang> guess 1 100 guessing a number between 1 and 100 is it 86? hi guessing a number between 1 and 85 is it 56? hi guessing a number between 1 and 55 is it 24? lo guessing a number between 25 and 55 is it 29? lo guessing a number between 30 and 55 is it 43? lo guessing a number between 44 and 55 is it 53? hi guessing a number between 44 and 52 is it 51? hi guessing a number between 44 and 50 is it 48? lo guessing a number between 49 and 50 is it 49? lo 50</lang>

This could be made more efficient by replacing guess=.lo+?hi-lo with guess=.<.-:lo+hi. (The above example would have finished on the first guess, but the range 1..100 would never take more than 6 guesses -- the remaining answers would be determined after six guesses.)

Java

A clever solution that uses the built-in binary search functions with a virtual list.

Translation of: Go

<lang java5>import java.util.AbstractList; import java.util.Collections; import java.util.Scanner;

public class GuessNumber {

   public static final int LOWER = 0, UPPER = 100;
   public static void main(String[] args) {

System.out.printf("Instructions:\n" + "Think of integer number from %d (inclusive) to %d (exclusive) and\n" + "I will guess it. After each guess, you respond with L, H, or C depending\n" + "on if my guess was too low, too high, or correct.\n", LOWER, UPPER); int result = Collections.binarySearch(new AbstractList<Integer>() { private final Scanner in = new Scanner(System.in); public int size() { return UPPER - LOWER; } public Integer get(int i) { System.out.printf("My guess is: %d. Is it too high, too low, or correct? (H/L/C) ", LOWER+i); String s = in.nextLine(); assert s.length() > 0; switch (Character.toLowerCase(s.charAt(0))) { case 'l': return -1; case 'h': return 1; case 'c': return 0; } return -1; } }, 0); if (result < 0) System.out.println("That is impossible."); else System.out.printf("Your number is %d.\n", result);

   }

}</lang>

JavaScript

Spidermonkey version

A boring solution that does nothing clever or inscrutable.

Well, it does use recursion for the guessing function, but that's OK because the depth is bounded by LOG2 of the range. That's not true if the user changes his number, but then he gets what he deserves.

<lang javascript>#!/usr/bin/env js

var DONE = RIGHT = 0, HIGH = 1, LOW = -1;

function main() {

   showInstructions();
   while (guess(1, 100) !== DONE);

}

function guess(low, high) {

   if (low > high) {
       print("I can't guess it. Perhaps you changed your number.");
       return DONE;
   }
   
   var g = Math.floor((low + high) / 2);
   var result = getResult(g);
   switch (result) {
       case RIGHT:
           return DONE;
       case LOW:
           return guess(g + 1, high);
       case HIGH:
           return guess(low, g - 1);
   }

}

function getResult(g) {

   while(true) {
       putstr('Is it ' + g + '? ');
       var ans = readline().toUpperCase().replace(/^\s+/, ) + ' ';
       switch (ans[0]) {
           case 'R':
               print('I got it! Thanks for the game.');
               return RIGHT;
           case 'L': 
               return LOW;
           case 'H':
               return HIGH;
           default:
               print('Please tell me if I am "high", "low" or "right".');
       }
   }

}

function showInstructions() {

   print('Think of a number between 1 and 100 and I will try to guess it.');
   print('After I guess, type "low", "high" or "right", and then press enter.');
   putstr("When you've thought of a number press enter.");
   readline();

}

main(); </lang>

An example session:

Think of a number between 1 and 100 and I will try to guess it.
After I guess, type "low", "high" or "right", and then press enter.
When you've thought of a number press enter.
Is it 50? high
Is it 25? high
Is it 12? low
Is it 18? high
Is it 15? high
Is it 13? right
I got it! Thanks for the game.

Another example session:

Think of a number between 1 and 100 and I will try to guess it.
After I guess, type "low", "high" or "right", and then press enter.
When you've thought of a number press enter.
Is it 50? n
Please tell me if I am "high", "low" or "right".
Is it 50? h
Is it 25? h
Is it 12? h
Is it 6? h
Is it 3? h
Is it 1? h
I can't guess it. Perhaps you changed your number.

Julia

This version uses the expression   to calculate the maximum number of guesses it will need.

<lang Julia>print("Enter an upper bound: ") lower = 0 input = readline() upper = parse(Int, input)

if upper < 1

   throw(DomainError)

end

attempts = 1 print("Think of a number, ", lower, "--", upper, ", then press ENTER.") readline() const maxattempts = round(Int, ceil(-log(1 / (upper - lower)) / log(2))) println("I will need at most ", maxattempts, " attempts ",

   "(⌈-log(1 / (", upper, " - ", lower, ")) / log(2)⌉ = ",
   maxattempts, ").\n")

previous = -1 guess = -1

while true

   previous = guess
   guess = lower + round(Int, (upper - lower) / 2, RoundNearestTiesUp)
   if guess == previous || attempts > maxattempts
       println("\nThis is impossible; did you forget your number?")
       exit()
   end
   print("I guess ", guess, ".\n[l]ower, [h]igher, or [c]orrect? ")
   input = chomp(readline())
   
   while input ∉ ["c", "l", "h"]
       print("Please enter one of \"c\", \"l\", or \"h\". ")
       input = chomp(readline())
   end
   if input == "l"
       upper = guess
   elseif input == "h"
       lower = guess
   else
       break
   end
   attempts += 1

end

println("\nI win after ", attempts, attempts == 1 ? " attempt." : " attempts.")</lang>

Kotlin

Translation of: FreeBASIC

<lang scala>// version 1.0.5-2

fun main(args: Array<String>) {

   var hle: Char 
   var lowest  = 1
   var highest = 20
   var guess   = 10
   println("Please choose a number between 1 and 20 but don't tell me what it is yet\n")
   while (true) {
       println("My guess is $guess")
       do {
           print("Is this higher/lower than or equal to your chosen number h/l/e : ")
           hle = readLine()!!.first().toLowerCase()
           if (hle == 'l' && guess == highest) { 
               println("It can't be more than $highest, try again") 
               hle = 'i' // signifies invalid
           }
           else if (hle == 'h' && guess == lowest) {
               println("It can't be less than $lowest, try again") 
               hle = 'i' 
           }
       }
       while (hle !in "hle")
  
       when (hle) {
           'e' -> { println("Good, thanks for playing the game with me!") ; return }
           'h' ->   if (highest > guess - 1) highest = guess - 1 
           'l' ->   if (lowest  < guess + 1) lowest  = guess + 1  
       }
       guess = (lowest + highest) / 2
   }

}</lang> Sample input/output:

Output:

<Please choose a number between 1 and 20 but don't tell me what it is yet

My guess is 10
Is this higher/lower or equal to your chosen number h/l/e : h
My guess is 5
Is this higher/lower or equal to your chosen number h/l/e : l
My guess is 7
Is this higher/lower or equal to your chosen number h/l/e : l
My guess is 8
Is this higher/lower or equal to your chosen number h/l/e : e
Good, thanks for playing the game with me!
/pre>

=={{header|Lasso}}==
<lang Lasso>#!/usr/bin/lasso9

local(
	mini=0,
	maxi=100,
	status	= false,
	count = 0,
	response,
	guess
)

stdoutnl('Think of a number between ' + #mini + ' and ' + #maxi + '
Each time I guess indicate if I was to high (H), to low (L) or just right (R).')


while(not #status) => {

	if(not(#mini <= #maxi)) => {

		stdout('I think you are trying to cheat me. I will not play anymore.')
		#status = true

	else

		#guess = ((#maxi - #mini) /2 ) + #mini

		stdout('You are thinking on ' + #guess + ' ')
		#response = null

		// the following bits wait until the terminal gives you back a line of input
		while(not #response or #response -> size == 0) => {
			#response = file_stdin -> readSomeBytes(1024, 1000)
		}
		#response -> replace(bytes('\n'), bytes(''))

		match(string(#response)) => {
			case('L')
				#mini = #guess + 1
				#count++
			case('H')
				#maxi = #guess - 1
				#count++
			case('R')
				stdout('Am I smart or smart! I guessed it in ' + #count ' tries!')
				#status = true
			case()
				stdout('Are you having issues reading instructions? ')
		}
	}
}</lang>

Examples:
<pre>Think of a number between 0 and 100
Each time I guess indicate if I was to high (H), to low (L) or just right (R).
You are thinking on 50 l
You are thinking on 75 l
You are thinking on 88 h
You are thinking on 81 r
Am I smart or smart! I guessed it in 4 tries!
Think of a number between 0 and 100
Each time I guess indicate if I was to high (H), to low (L) or just right (R).
You are thinking on 50 k
Are you having issues reading instructions? You are thinking on 50 tr
Are you having issues reading instructions? You are thinking on 50 l
You are thinking on 75 l
You are thinking on 88 l
You are thinking on 94 l
You are thinking on 97 l
You are thinking on 99 h
You are thinking on 98 r
Am I smart or smart! I guessed it in 6 tries!
You are thinking on 50 h
You are thinking on 24 h
You are thinking on 11 l
You are thinking on 17 l
You are thinking on 20 l
You are thinking on 22 l
You are thinking on 23 l
I think you are trying to cheat me. I will not play anymore.

Liberty BASIC

<lang lb>mini=0 maxi=100

print "Think of a number between ";mini;" and ";maxi print "Each time I guess a number you must state whether my" print "guess was too high, too low, or equal to your number." print

while response$<>"="

  if not(mini<=maxi) then 

print "Error" exit while end if guess=int((maxi-mini)/2)+mini print "My guess is ";guess;". Type L for low, H for high, = for correct." input response$ response$=upper$(response$) select case response$ case "L" mini=guess+1 case "H"

        maxi=guess-1

case "=" print guess;" is correct." exit while case else print "Your response was not helpful." end select

wend

print "Thanks for playing." </lang>

Lua

<lang>function wait(waittime)--wait function is used so that app will not quit immediately

 local timer = os.time()
 repeat until os.time() == timer + waittime

end


upperBound = 100 lowerBound = 0 print("Think of an integer between 1 to 100.") print("I will try to guess it.") while true do upper1 = upperBound+1 upper2 = upperBound-1 if upperBound == lowerBound or upper1 == lowerBound or upper2 == lowerBound or lowerBound > upperBound then--make sure player is not cheating io.write("You're cheating! I'm not playing anymore. Goodbye.") wait(3) break else Guess = math.floor((upperBound + lowerBound)/2)--guessing mechanism print("My guess is: "..Guess..". Is it too high, too low, or correct? (h/l/c)") input = io.read()

if input == "h" then --higher upperBound = Guess elseif input == "l" then --lower lowerBound = Guess elseif input == "c" then --correct io.write("So I win? Thanks for playing with me.") wait(3) break else print("Invalid input. Please try again. ") end end end </lang>

Mathematica / Wolfram Language

<lang>guessnumber[min0_, max0_] :=

 DynamicModule[{min = min0, max = max0, guess, correct = False}, 
  guess[] := Round@Mean@{min, max}; 
  Dynamic@If[correct, Row@{"Your number is ", guess[], "."}, 
    Column@{Row@{"I guess ", guess[], "."}, 
      Row@{Button["too high", max = guess[]], 
        Button["too low", min = guess[]],
        Button["correct", correct = True]}}]];

guessnumber[1, 100]</lang>

MATLAB

<lang MATLAB>function GuessNumberFeedbackPlayer

   lowVal = input('Lower limit: ');
   highVal = input('Upper limit: ');
   fprintf('Think of your number. Press Enter when ready.\n')
   pause
   nGuesses = 1;
   done = false;
   while ~done
       guess = floor(0.5*(lowVal+highVal));
       score = input(sprintf( ...
           'Is %d too high (H), too low (L), or equal (E)? ', guess), 's');
       if any(strcmpi(score, {'h' 'hi' 'high' 'too high' '+'}))
           highVal = guess-1;
           nGuesses = nGuesses+1;
       elseif any(strcmpi(score, {'l' 'lo' 'low' 'too low' '-'}))
           lowVal = guess+1;
           nGuesses = nGuesses+1;
       elseif any(strcmpi(score, {'e' 'eq' 'equal' 'right' 'correct' '='}))
           fprintf('Yay! I win in %d guesses.\n', nGuesses)
           done = true;
       else
           fprintf('Unclear response. Try again.\n')
       end
       if highVal < lowVal
           fprintf('Incorrect scoring. No further guesses.\n')
           done = true;
       end
   end

end</lang>

Output:
Lower limit: 0
Upper limit: 50
Think of your number. Press Enter when ready.
Is 25 too high (H), too low (L), or equal (E)? L
Is 38 too high (H), too low (L), or equal (E)? H
Is 31 too high (H), too low (L), or equal (E)? H
Is 28 too high (H), too low (L), or equal (E)? L
Is 29 too high (H), too low (L), or equal (E)? E
Yay! I win in 5 guesses.
Lower limit: 0
Upper limit: 10
Think of your number. Press Enter when ready.
Is 5 too high (H), too low (L), or equal (E)? L
Is 8 too high (H), too low (L), or equal (E)? hello
Unclear response. Try again.
Is 8 too high (H), too low (L), or equal (E)? H
Is 6 too high (H), too low (L), or equal (E)? L
Is 7 too high (H), too low (L), or equal (E)? H
Incorrect scoring. No further guesses.

MAXScript

<lang MAXScript>inclusiveRange = [1,100] lowRange = inclusiveRange.x maxRange = inclusiveRange.y guesses = 1 inf = "Think of a number between % and % and I will try to guess it.\n" +\ "Type -1 if the guess is less than your number,\n"+\ "0 if the guess is correct, " +\ "or 1 if it's too high.\nPress esc to exit.\n" clearListener() format inf (int lowRange) (int maxRange) while not keyboard.escpressed do ( local chosen = ((lowRange + maxRange) / 2) as integer if lowRange == maxRange do format "\nHaving fun?" format "\nI choose %.\n" chosen local theAnswer = getKBValue prompt:"Answer? " case theAnswer of ( (-1): (lowRange = chosen; guesses += 1) (0): (format "\nYay. I guessed your number after % %.\n" \ guesses (if guesses == 1 then "try" else "tries") exit with OK) (1): (maxRange = chosen; guesses += 1) default: (format "\nI don't understand your input.") ) )</lang>

Output:

<lang MAXScript> OK Think of a number between 1 and 100 and I will try to guess it. Type -1 if the guess is less than your number, 0 if the guess is correct, or 1 if it's too high. Press esc to exit. OK

I choose 50. Answer? -1 I choose 75. Answer? -1 I choose 87. Answer? 1 I choose 81. Answer? -1 I choose 84. Answer? -1 I choose 85. Answer? 0 Yay. I guessed your number after 6 tries. OK </lang>

Modula-2

<lang modula2>MODULE raden;

IMPORT InOut;

VAR done, ok  : BOOLEAN;

       guess, upp, low         : CARDINAL;
       res                     : CHAR;

BEGIN

 InOut.WriteString ("Choose a number between 0 and 1000.");
 InOut.WriteLn;
 InOut.WriteLn;
 upp := 1000;
 low := 0;
 REPEAT
   ok := FALSE;
   guess := ( ( upp - low ) DIV 2 ) + low;
   InOut.WriteString ("My guess is");  InOut.WriteCard (guess, 4);     InOut.Write (11C);
   InOut.WriteString ("How did I score? 'L' = too low, 'H' = too high, 'Q' = OK : ");
   InOut.WriteBf;
   REPEAT
     InOut.Read (res);
     res := CAP (res)
   UNTIL  (res = 'Q') OR (res = 'L') OR (res = 'H');
   CASE  res  OF
     'L'       : low := guess  |
     'H'       : upp := guess
   ELSE
     ok := TRUE
   END;
 UNTIL ok;
 InOut.WriteString ("So the number is");       InOut.WriteCard (guess, 4);
 InOut.WriteLn;
 InOut.WriteString ("Thanks for letting me play with you.");
 InOut.WriteLn

END raden.</lang>Example:

raden
Choose a number between 0 and 1000.

My guess is 500 How did I score? 'L' = too low, 'H' = too high, 'Q' = OK : l
My guess is 750 How did I score? 'L' = too low, 'H' = too high, 'Q' = OK : h
My guess is 625 How did I score? 'L' = too low, 'H' = too high, 'Q' = OK : h
My guess is 562 How did I score? 'L' = too low, 'H' = too high, 'Q' = OK : l
My guess is 593 How did I score? 'L' = too low, 'H' = too high, 'Q' = OK : l
My guess is 609 How did I score? 'L' = too low, 'H' = too high, 'Q' = OK : h
My guess is 601 How did I score? 'L' = too low, 'H' = too high, 'Q' = OK : h
My guess is 597 How did I score? 'L' = too low, 'H' = too high, 'Q' = OK : l
My guess is 599 How did I score? 'L' = too low, 'H' = too high, 'Q' = OK : l
My guess is 600 How did I score? 'L' = too low, 'H' = too high, 'Q' = OK : q
So the number is 600
Thanks for letting me play with you.

Nim

<lang nim>import strutils

let oRange = 1..10 var iRange = oRange

echo """Think of a number between $# and $# and wait for me to guess it. On every guess of mine you should state whether the guess was too high, too low, or equal to your number by typing h, l, or =""".format(iRange.a, iRange.b)

var i = 0 while true:

 inc i
 let guess = (iRange.a + iRange.b) div 2
 stdout.write "Guess $# is: $#. The score for which is (h,l,=): ".format(i, guess)
 let txt = stdin.readLine()
 case txt
 of "h": iRange.b = guess - 1
 of "l": iRange.a = guess + 1
 of "=":
   echo "  Ye-Haw!!"
   break
 else: echo "  I don't understand your input of '%s'?".format(txt)
 if iRange.a > iRange.b or iRange.a < oRange.a or iRange.b > oRange.b:
   echo "Please check your scoring as I cannot find the value"
   break

echo "Thanks for keeping score."</lang> Output:

Think of a number between 1 and 10 and wait for me to guess it.
On every guess of mine you should state whether the guess was
too high, too low, or equal to your number by typing h, l, or =
Guess 1 is: 5. The score for which is (h,l,=): l
Guess 2 is: 8. The score for which is (h,l,=): h
Guess 3 is: 6. The score for which is (h,l,=): l
Guess 4 is: 7. The score for which is (h,l,=): =
  Ye-Haw!!
Thanks for keeping score.

NS-HUBASIC

<lang NS-HUBASIC>10 PRINT "THINK OF A NUMBER BETWEEN 1 AND";" 9, AND I'LL TRY TO GUESS IT." 20 ISVALID=0 30 GUESS=5 40 PRINT "I GUESS"GUESS"." 50 INPUT "IS THAT HIGHER THAN, LOWER THAN OR EQUAL TO YOUR NUMBER? ",ANSWER$ 60 IF ANSWER$="LOWER THAN" THEN ISVALID=1:IF GUESS<9 THEN GUESS=GUESS+1 70 IF ANSWER$="HIGHER THAN" THEN ISVALID=1:IF GUESS>1 THEN GUESS=GUESS-1 80 IF ANSWER$="EQUAL TO" THEN PRINT "OH YES! I GUESSED CORRECTLY!":END 90 IF ISVALID=0 THEN PRINT "SORRY";", BUT THAT ANSWER IS INVALID." 100 GOTO 40</lang>

Objective-C

A clever solution that uses the built-in binary search functions with a virtual list.

Translation of: Java

<lang objc>#import <Foundation/Foundation.h>

@interface GuessNumberFakeArray : NSArray {

 int lower, upper;

} - (instancetype)initWithLower:(int)l andUpper:(int)u; @end

@implementation GuessNumberFakeArray - (instancetype)initWithLower:(int)l andUpper:(int)u {

 if ((self = [super init])) {
   lower = l;
   upper = u;
 }
 return self;

} - (NSUInteger)count { return upper-lower; } - (id)objectAtIndex:(NSUInteger)i {

 printf("My guess is: %d. Is it too high, too low, or correct? (H/L/C) ", lower + (int)i);
 char input[2] = " ";
 scanf("%1s", input);
 switch (tolower(input[0])) {
   case 'l':
     return @-1;
   case 'h':
     return @1;
   case 'c':
     return @0;
 }
 return nil;

} @end

  1. define LOWER 0
  2. define UPPER 100

int main(int argc, const char *argv[]) {

 @autoreleasepool {
 
   printf("Instructions:\n"
          "Think of integer number from %d (inclusive) to %d (exclusive) and\n"
          "I will guess it. After each guess, you respond with L, H, or C depending\n"
          "on if my guess was too low, too high, or correct.\n",
          LOWER, UPPER);
   NSUInteger result = [[[GuessNumberFakeArray alloc] initWithLower:LOWER andUpper:UPPER]
                        indexOfObject:[NSNumber numberWithInt: 0]
                        inSortedRange:NSMakeRange(0, UPPER - LOWER)
                              options:0
                      usingComparator:^(id x, id y){ return [x compare: y]; }];
   if (result == NSNotFound)
     printf("That is impossible.\n");
   else
     printf("Your number is %d.", LOWER + (int)result);
 
 }
 return 0;

}</lang>

PARI/GP

<lang parigp> guessnumber2(b)={ my(c=0,d=b,a=0); for(x=1,b,

   for(y=1,b,
       if(a<c||a==c||a==d||a>d,
          a=random(b),
          break()
         )
    );
    print("I guess "a" am I h,l,or e ?");
    g=input();
    if(g==h,
    d=a,
    if(g==l,
       c=a,
       if(g==e,
          break()
       )
    )
 )
);

} </lang>

Pascal

<lang pascal>Program GuessIt(input, output);

var

 done, ok:        boolean;
 guess, upp, low: integer;
 res:             char;

begin

 writeln ('Choose a number between 0 and 1000.');
 write ('Press Enter and I will start to guess the number.');
 readln;
 upp := 1000;
 low := 0;
 repeat
   ok := false;
   guess := ( ( upp - low ) div 2 ) + low;
   write ('My guess is: ', guess:4);
   write ('. How did i score? l = too low, h = too high, c = correct : ');
   repeat
     readln (res);
     res := lowercase(res);
   until (res = 'c') or (res = 'l') or (res = 'h');
   case  res  of
     'l': low := guess;
     'h': upp := guess;
   else
     ok := true
   end;
 until ok;
 writeln ('So the number is: ', guess:4);
 writeln ('It was nice to play with you.');

end.</lang> Output:

:> ./GuessTheNumberPlayerFeedback
Choose a number between 0 and 1000.
Press Enter and I will start to guess the number.
My guess is:  500. How did i score? 'l' = too low, 'h' = too high, 'c' = correct : h
My guess is:  250. How did i score? 'l' = too low, 'h' = too high, 'c' = correct : h
My guess is:  125. How did i score? 'l' = too low, 'h' = too high, 'c' = correct : l
My guess is:  187. How did i score? 'l' = too low, 'h' = too high, 'c' = correct : h
My guess is:  156. How did i score? 'l' = too low, 'h' = too high, 'c' = correct : h
My guess is:  140. How did i score? 'l' = too low, 'h' = too high, 'c' = correct : h
My guess is:  132. How did i score? 'l' = too low, 'h' = too high, 'c' = correct : l
My guess is:  136. How did i score? 'l' = too low, 'h' = too high, 'c' = correct : l
My guess is:  138. How did i score? 'l' = too low, 'h' = too high, 'c' = correct : h
My guess is:  137. How did i score? 'l' = too low, 'h' = too high, 'c' = correct : c
So the number is:  137
It was nice to play with you.

Perl

<lang perl>#!/usr/bin/perl

my $min = 1; my $max = 99; my $guess = int(rand $max) + $min; my $tries = 0;

print "=>> Think of a number between $min and $max and I'll guess it!\n Press <ENTER> when are you ready... ";

<STDIN>;

{

   do {
       $tries++;
       print "\n=>> My guess is: $guess Is your number higher, lower, or equal? (h/l/e)\n> ";
       my $score = <STDIN>;
       if ($max <= $min) {
           print "\nI give up...\n" and last;
       } elsif ($score =~ /^h/i) {
           $min = $guess + 1;
       } elsif ($score =~ /^l/i) {
           $max = $guess;
       } elsif ($score =~ /^e/i) {
           print "\nI knew it! It took me only $tries tries.\n" and last;
       } else {
           print "error: invalid score\n";
       }   
       $guess = int(($max + $min) / 2); 
   } while(1);

}</lang>

=>> Think of a number between 1 and 99 and I'll guess it!

Press <ENTER> when are you ready... 

=>> My guess is: 88. Is your number higher, lower or equal? (h/l/e)
> l

=>> My guess is: 44. Is your number higher, lower or equal? (h/l/e)
> l

=>> My guess is: 22. Is your number higher, lower or equal? (h/l/e)
> h

=>> My guess is: 33. Is your number higher, lower or equal? (h/l/e)
> l

=>> My guess is: 28. Is your number higher, lower or equal? (h/l/e)
> e

I knew it! It took me only 5 tries.

Phix

--
-- demo\rosetta\Guess_the_number2.exw
--
with javascript_semantics -- (spacing not (yet) great...)
include pGUI.e
Ihandle lbl, guess, toohigh, too_low, correct, newgame, dlg

integer Min=0, Max=100, Guess
constant LTHINK = sprintf("Think of a number between %d and %d.",{Min,Max})

procedure set_active(bool bActive)
    IupSetInt({toohigh, too_low, correct},"ACTIVE",bActive)
    IupSetInt(newgame,"ACTIVE",not bActive)
end procedure

procedure set_guess()
    Guess = floor((Max+Min)/2)
    string title = sprintf("My guess is %d, is this too high, too low, or correct?", Guess)
    if Max<Min then
        set_active(false)
        title = "I think something is strange here..."
    end if
    IupSetStrAttribute(guess,"TITLE",title)
    IupRefresh(guess)
end procedure

function click_cb(Ihandle ih)
    switch substitute(IupGetAttribute(ih,"TITLE"),"Too ","")[1] do
        case 'H':   Max = Guess-1  set_guess()
        case 'L':   Min = Guess+1  set_guess()
        case 'C':   IupSetStrAttribute(guess,"TITLE","I did it!")
                    set_active(false)
        case 'N':   Min = 0  Max = 100  set_guess()
                    set_active(true)
    end switch
    return IUP_DEFAULT
end function

procedure main()
    IupOpen()
    lbl = IupLabel(LTHINK)
    guess = IupLabel("")
    toohigh = IupButton("Too High", Icallback("click_cb"))
    too_low = IupButton("Too Low", Icallback("click_cb"))
    correct = IupButton("Correct", Icallback("click_cb"))
    newgame = IupButton("New Game", Icallback("click_cb"), "ACTIVE=NO")
    dlg = IupDialog(IupVbox({lbl,
                             guess,
                             IupHbox({toohigh,too_low,correct,newgame},
                                     "GAP=10")},
                            `NMARGIN=15x15,GAP=10`),
                    `MINSIZE=300x100,TITLE="Guess the number2"`)
    set_guess()
    IupShow(dlg)
    if platform()!=JS then
        IupMainLoop()
        IupClose()
    end if
end procedure
 
main()

PicoLisp

Translation of: PureBasic

<lang PicoLisp>(de guessTheNumber (Min Max)

  (prinl "Think of a number between " Min " and " Max ".")
  (prinl "On every guess of mine you should state whether my guess was")
  (prinl "too high, too low, or equal to your number by typing 'h', 'l', Or '='")
  (use Guess
     (loop
        (NIL (> Max Min)
           (prinl "I think somthing is strange here...") )
        (prin
           "My guess is "
           (setq Guess (+ Min (/ (- Max Min) 2)))
           ",is this correct? " )
        (flush)
        (NIL
           (case (uppc (car (line)))
              ("H" (setq Max Guess))
              ("L" (setq Min Guess))
              ("=" (nil (prinl "I did it!")))
              (T (prinl "I do not understand that...")) ) ) ) ) )</lang>

Output:

: (guessTheNumber 1 99)
Think of a number between 1 and 99.
On every guess of mine you should state whether my guess was
too high, too low, or equal to your number by typing 'h', 'l', Or '='
My guess is 50,is this correct? h
My guess is 25,is this correct? h
My guess is 13,is this correct? l
My guess is 19,is this correct? l
My guess is 22,is this correct? =
I did it!

Prolog

<lang prolog>min(1). max(10).

pick_number(Min, Max) :-

   min(Min), max(Max),
   format('Pick a number between ~d and ~d, and I will guess it...~nReady? (Enter anything when ready):', [Min, Max]),
   read(_).

guess_number(Min, Max) :-

   Guess is (Min + Max) // 2,
   format('I guess ~d...~nAm I correct (c), too low (l), or too high (h)? ', [Guess]),
   repeat,
       read(Score),
       ( Score = l -> NewMin is Guess + 1, guess_number(NewMin, Max)
       ; Score = h -> NewMax is Guess - 1, guess_number(Min, NewMax)
       ; Score = c -> writeln('I am correct!')
       ; writeln('Invalid input'),
         false
       ).

play :-

   pick_number(Min, Max),
   guess_number(Min, Max).</lang>

Example:

<lang prolog>?- play. Pick a number between 1 and 10, and I will guess it... Ready? (Enter anything when ready):y. I guess 5... Am I correct (c), too low (l), or too high (h)? h. I guess 2... Am I correct (c), too low (l), or too high (h)? l. I guess 3... Am I correct (c), too low (l), or too high (h)? c. I'm correct! true</lang>

PureBasic

<lang PureBasic>min=0 max=100

If OpenConsole()

 PrintN("Think of a number between "+Str(min)+" and "+Str(max)+".")
 PrintN("On every guess of mine you should state whether my guess was")
 PrintN("too high, too low, or equal to your number by typing 'h', 'l', Or '='")
 Repeat
   If max<=min
     PrintN("I think somthing is strange here...")
     Break
   EndIf
   Guess=(max-min)/2+min
   Print("My guess is "+Str(Guess)+",is this correct? "): Respons.s=UCase(Input())
   If Respons="H":     max=Guess-1
   ElseIf Respons="L": min=Guess+1
   ElseIf Respons="="
     PrintN("I did it!")
     Break
   Else
     PrintN("I do not understand that...")
   EndIf
 ForEver

EndIf</lang>

Python

<lang python>inclusive_range = mn, mx = (1, 10)

print(\ Think of a number between %i and %i and wait for me to guess it. On every guess of mine you should state whether the guess was too high, too low, or equal to your number by typing h, l, or =  % inclusive_range)

i = 0 while True:

   i += 1
   guess = (mn+mx)//2
   txt = input("Guess %2i is: %2i. The score for which is (h,l,=): "
               % (i, guess)).strip().lower()[0]
   if txt not in 'hl=':
       print("  I don't understand your input of '%s' ?" % txt)
       continue
   if txt == 'h':
       mx = guess-1
   if txt == 'l':
       mn = guess+1
   if txt == '=':
       print("  Ye-Haw!!")
       break
   if (mn > mx) or (mn < inclusive_range[0]) or (mx > inclusive_range[1]):
       print("Please check your scoring as I cannot find the value")
       break
       

print("\nThanks for keeping score.")</lang>

Sample Game-play

Think of a number between 1 and 10 and wait for me to guess it.
On every guess of mine you should state whether the guess was
too high, too low, or equal to your number by typing h, l, or =

Guess  1 is:  5. The score for which is (h,l,=): l
Guess  2 is:  8. The score for which is (h,l,=): l
Guess  3 is:  9. The score for which is (h,l,=): l
Guess  4 is: 10. The score for which is (h,l,=): =
  Ye-Haw!!

Thanks for keeping score.

Obscure solution using bisect module

Hacky solution using a fake list class and the bisect module from the standard library to do the binary search.

Translation of: Go

<lang python>import bisect try: input = raw_input except: pass

class GuessNumberFakeList(object):

   def __getitem__(self, i):
       s = input("Is your number less than or equal to %d?" % i)
       return 0 if s.lower().startswith('y') else -1

LOWER, UPPER = 0, 100

if __name__ == "__main__":

   print("""Instructions:

Think of integer number from %d (inclusive) to %d (exclusive) and I will guess it. After each guess, I will ask you if it is less than or equal to some number, and you will respond with "yes" or "no". """ % (LOWER, UPPER))

   result = bisect.bisect_left(GuessNumberFakeList(), 0, LOWER, UPPER)
   print("Your number is %d." % result)</lang>
Sample output
Instructions:
Think of integer number from 0 (inclusive) to 100 (exclusive) and
I will guess it. After each guess, I will ask you if it is less than
or equal to some number, and you will respond with "yes" or "no".


Is your number less than or equal to 50?no

Is your number less than or equal to 75?yes

Is your number less than or equal to 63?no

Is your number less than or equal to 69?no

Is your number less than or equal to 72?yes

Is your number less than or equal to 71?no
Your number is 72.

R

Can be fooled if you lie to it. For example, always reporting "h" for guessANumberPlayer(1,5) will have it guess 0. <lang rsplus>guessANumberPlayer<-function(low,high) {

 boundryErrorCheck(low,high)
 repeat
 {
   guess<-floor(mean(c(low,high)))
   #Invalid inputs to this switch will simply cause the repeat loop to run again, breaking nothing.
   switch(guessResult(guess),
          l = low<-guess+1,
          h = high<-guess-1,
          c = return(paste0("Your number is ",guess,"."," I win!")))
 }

}

  1. Copied from my solution at https://rosettacode.org/wiki/Guess_the_number/With_feedback#R

boundryErrorCheck<-function(low,high) {

 if(!is.numeric(low)||as.integer(low)!=low){stop("Lower bound must be an integer. Try again.")}
 if(!is.numeric(high)||as.integer(high)!=high){stop("Upper bound must be an integer. Try again.")}
 if(high<low){stop("Upper bound must be strictly greater than lower bound. Try again.")}
 if(low==high){stop("This game is impossible to lose. Try again.")}
 invisible()

}

guessResult<-function(guess) {

 readline(paste0("My guess is ",guess,". If it is too low, submit l. If it is too high, h. Otherwise, c. "))

}</lang>

Racket

<lang Racket>#lang racket

(define (guess low high)

 (define (input-loop available)
   (define input (car (string->list (symbol->string (read)))))
   (if (member input available)
       input
       (begin
         (printf "Invalid Input\n") (input-loop available))))
 
 (define (guess-loop low high)
   (define guess (floor (/ (+ low high) 2)))
   (printf "My guess is ~a.\n" guess)
   (define input (input-loop (list #\c #\l #\h)))
   (case input
     ((#\c) (displayln "I knew it!\n"))
     ((#\l) (guess-loop low (sub1 guess)))
     ((#\h) (guess-loop (add1 guess) high))))
 
 (printf "Think of a number between ~a and ~a.

Use (h)igh, (l)ow and (c)orrect to guide me.\n" low high)

 (guess-loop low high))</lang>

Another way with loops and mutation <lang Racket>#lang racket (define (guess minimum maximum)

 (printf "Think of a number from ~a to ~a, use (h)igh, (l)ow and (c)orrect." minimum maximum)
 
 (define input "")
 
 (do ((guess (round (/ (+ maximum minimum) 2))  (round (/ (+ maximum minimum) 2))))
   ((string=? input "c"))
   (printf "My guess is: ~a\n(h/l/=) > ")
   (when (string=? input "h")
     (begin (display "OK...")
              (set! maximum (sub1 guess))))
       (when (string=? input "l")
         (begin (display "OK...")
                (set! minimum (add1 guess)))))
 (displayln "I was RIGHT!"))</lang>

Raku

(formerly Perl 6)

<lang perl6>multi sub MAIN() { MAIN(0, 100) } multi sub MAIN($min is copy where ($min >= 0), $max is copy where ($max > $min)) {

   say "Think of a number between $min and $max and I'll guess it!";
   while $min <= $max {
       my $guess = (($max + $min)/2).floor;
       given lc prompt "My guess is $guess. Is your number higher, lower or equal? " {
           when /^e/ { say "I knew it!"; exit }
           when /^h/ { $min = $guess + 1      }
           when /^l/ { $max = $guess          }
           default   { say "WHAT!?!?!"        }
       }
   }
   say "How can your number be both higher and lower than $max?!?!?";

}</lang>

You may execute this program with 'raku program' or with 'raku program min max'. Raku creates a usage for us if we don't give the right parameters. It also parses the parameters for us and provides them via $min and $max. We use multi-subs to provide two MAIN subroutines so the user is able to choose between min and max parameters and no parameters at all, in which case min is set to 0 and max to 100.

Red

<lang rebol>Red[]

lower: 1 upper: 100 print ["Please think of a number between" lower "and" upper]

forever [

   guess: to-integer upper + lower / 2
   print ["My guess is" guess]
   until [
       input: ask "Is your number (l)ower, (e)qual to, or (h)igher than my guess? "
       find ["l" "e" "h"] input
   ]
   if "e" = input [break]
   either "l" = input [upper: guess] [lower: guess]

]

print ["I did it! Your number was" guess]</lang>

Output:
Please think of a number between 1 and 100
My guess is 50
Is your number (l)ower, (e)qual to, or (h)igher than my guess? car
Is your number (l)ower, (e)qual to, or (h)igher than my guess? l
My guess is 25
Is your number (l)ower, (e)qual to, or (h)igher than my guess? h
My guess is 37
Is your number (l)ower, (e)qual to, or (h)igher than my guess? l
My guess is 31
Is your number (l)ower, (e)qual to, or (h)igher than my guess? h
My guess is 34
Is your number (l)ower, (e)qual to, or (h)igher than my guess? e
I did it! Your number was 34

REXX

with positive integers

This version only handles positive integers up to the nine decimal digits,   but the default HIGH is one thousand. <lang rexx>/*REXX program plays guess─the─number (with itself) with positive integers. */ parse arg low high seed . /*obtain optional arguments from the CL*/ if low== | low=="," then low= 1 /*Not specified? Then use the default.*/ if high== | high=="," then high= 1000 /* " " " " " " */ if datatype(seed, 'W') then call random ,,seed /*Useful seed? Then use a random seed.*/ ?= random(low, high) /*generate random number from low->high*/ $= "──────── Try to guess my number (it's between " /*part of a prompt message.*/ g= /*nullify the first guess. */

   do #=1;                        oldg= g       /*save the guess for later comparison. */
   if pos('high', info)\==0  then high= g       /*test if the guess is too  high.      */
   if pos('low' , info)\==0  then low = g       /*  "   "  "    "    "  "   low.       */
   say                                          /*display a blank line before prompt.  */
   say $ low  '  and  '   high  "  inclusive):" /*issue the prompt message to terminal.*/
   say                                          /*display a blank line  after prompt.  */
   g= (low +  (high - low) / 2)   / 1           /*calculate the next guess & normalize.*/
   if g=oldg   then g= g + 1                    /*bump guess by one 'cause we're close.*/
   say 'My guess is'       g                    /*display computer's guess to the term.*/
   if g=?  then leave                           /*this guess is correct; leave & inform*/
   if g>?  then info= right(' Your guess is too high.', 60, "─")
           else info= right(' Your guess is too low.' , 60, "─")
   say info
   end   /*try*/

say /*stick a fork in it, we're all done. */ say 'Congratulations! You guessed the secret number in' # "tries."</lang> output shown is from playing several games:

──────── Try to guess my number  (it's between   1   and   1000   inclusive):

My guess is 500.5
──────────────────────────────────── Your guess is too high.

──────── Try to guess my number  (it's between   1   and   500.5   inclusive):

My guess is 250.75
───────────────────────────────────── Your guess is too low.

──────── Try to guess my number  (it's between   250.75   and   500.5   inclusive):

My guess is 375.625
──────────────────────────────────── Your guess is too high.

──────── Try to guess my number  (it's between   250.75   and   375.625   inclusive):

My guess is 313.1875
───────────────────────────────────── Your guess is too low.

──────── Try to guess my number  (it's between   313.1875   and   375.625   inclusive):

My guess is 344.40625
──────────────────────────────────── Your guess is too high.

──────── Try to guess my number  (it's between   313.1875   and   344.40625   inclusive):

My guess is 328.796875
───────────────────────────────────── Your guess is too low.

──────── Try to guess my number  (it's between   328.796875   and   344.40625   inclusive):

My guess is 336.601563
──────────────────────────────────── Your guess is too high.

──────── Try to guess my number  (it's between   328.796875   and   336.601563   inclusive):

My guess is 332.699219
──────────────────────────────────── Your guess is too high.

──────── Try to guess my number  (it's between   328.796875   and   332.699219   inclusive):

My guess is 330.748047
──────────────────────────────────── Your guess is too high.

──────── Try to guess my number  (it's between   328.796875   and   330.748047   inclusive):

My guess is 329.772461
───────────────────────────────────── Your guess is too low.

──────── Try to guess my number  (it's between   329.772461   and   330.748047   inclusive):

My guess is 330.260254
──────────────────────────────────── Your guess is too high.

──────── Try to guess my number  (it's between   329.772461   and   330.260254   inclusive):

My guess is 330.016358
──────────────────────────────────── Your guess is too high.

──────── Try to guess my number  (it's between   329.772461   and   330.016358   inclusive):

My guess is 329.89441
───────────────────────────────────── Your guess is too low.

──────── Try to guess my number  (it's between   329.89441   and   330.016358   inclusive):

My guess is 329.955384
───────────────────────────────────── Your guess is too low.

──────── Try to guess my number  (it's between   329.955384   and   330.016358   inclusive):

My guess is 329.985871
───────────────────────────────────── Your guess is too low.

──────── Try to guess my number  (it's between   329.985871   and   330.016358   inclusive):

My guess is 330.001115
──────────────────────────────────── Your guess is too high.

──────── Try to guess my number  (it's between   329.985871   and   330.001115   inclusive):

My guess is 329.993493
───────────────────────────────────── Your guess is too low.

──────── Try to guess my number  (it's between   329.993493   and   330.001115   inclusive):

My guess is 329.997304
───────────────────────────────────── Your guess is too low.

──────── Try to guess my number  (it's between   329.997304   and   330.001115   inclusive):

My guess is 329.99921
───────────────────────────────────── Your guess is too low.

──────── Try to guess my number  (it's between   329.99921   and   330.001115   inclusive):

My guess is 330.000163
──────────────────────────────────── Your guess is too high.

──────── Try to guess my number  (it's between   329.99921   and   330.000163   inclusive):

My guess is 329.999687
───────────────────────────────────── Your guess is too low.

──────── Try to guess my number  (it's between   329.999687   and   330.000163   inclusive):

My guess is 329.999925
───────────────────────────────────── Your guess is too low.

──────── Try to guess my number  (it's between   329.999925   and   330.000163   inclusive):

My guess is 330.000044
──────────────────────────────────── Your guess is too high.

──────── Try to guess my number  (it's between   329.999925   and   330.000044   inclusive):

My guess is 329.999985
───────────────────────────────────── Your guess is too low.

──────── Try to guess my number  (it's between   329.999985   and   330.000044   inclusive):

My guess is 330.000015
──────────────────────────────────── Your guess is too high.

──────── Try to guess my number  (it's between   329.999985   and   330.000015   inclusive):

My guess is 330

Congratulations!   You guessed the secret number in 26 tries.

with positive numbers

This version handles decimal fractions,   the method used can generate numbers from zero to five fractional digits. <lang rexx>/*REXX program plays guess─the─number (with itself) with positive rational numbers. */ parse arg low high frac seed . /*obtain optional arguments from the CL*/ if low== | low=="," then low= 1 /*Not specified? Then use the default.*/ if high== | high=="," then high= 1000 /* " " " " " " */ if frac== | frac=="," then frac= 1 /* " " " " " " */ if datatype(seed, 'W') then call random ,,seed /*Useful seed? Then use a random seed.*/ fdigs= 10**frac /*compute the number of fractional digs*/ ?= random(low, high) + random(0,fdigs) / fdigs /*Tougher game? It may have fractions.*/ $= "──────── Try to guess my number (it's between " /*part of a prompt message.*/ g= /*nullify the first guess. */

   do #=1;                        oldg= g       /*save the guess for later comparison. */
   if pos('high', info)\==0  then high= g       /*test if the guess is too  high.      */
   if pos('low' , info)\==0  then low = g       /*  "   "  "    "    "  "   low.       */
   say                                          /*display a blank line before prompt.  */
   say $ low  '  and  '   high  "  inclusive):" /*issue the prompt message to terminal.*/
   say                                          /*display a blank line  after prompt.  */
   g= (low +  (high - low) / 2)   / 1           /*calculate the next guess & normalize.*/
   if g=oldg   then g= g + 1                    /*bump guess by one 'cause we're close.*/
   say 'My guess is'       g                    /*display computer's guess to the term.*/
   if g=?  then leave                           /*this guess is correct; leave & inform*/
   if g>?  then info= right(' Your guess is too high.', 60, "─")
           else info= right(' Your guess is too low.' , 60, "─")
   say info
   end   /*try*/

say /*stick a fork in it, we're all done. */ say 'Congratulations! You guessed the secret number in' # "tries.""</lang> output will generally be about ten times longer (that is, has ten times the guesses) as the previous REXX version.

──────── Try to guess my number  (it's between   1   and   1000   inclusive):

My guess is 500.5
──────────────────────────────────── Your guess is too high.

──────── Try to guess my number  (it's between   1   and   500.5   inclusive):

My guess is 250.75
───────────────────────────────────── Your guess is too low.

──────── Try to guess my number  (it's between   250.75   and   500.5   inclusive):

My guess is 375.625
──────────────────────────────────── Your guess is too high.

──────── Try to guess my number  (it's between   250.75   and   375.625   inclusive):

My guess is 313.1875
───────────────────────────────────── Your guess is too low.

──────── Try to guess my number  (it's between   313.1875   and   375.625   inclusive):

My guess is 344.40625
──────────────────────────────────── Your guess is too high.

──────── Try to guess my number  (it's between   313.1875   and   344.40625   inclusive):

My guess is 328.796875
───────────────────────────────────── Your guess is too low.

──────── Try to guess my number  (it's between   328.796875   and   344.40625   inclusive):

My guess is 336.601563
──────────────────────────────────── Your guess is too high.

──────── Try to guess my number  (it's between   328.796875   and   336.601563   inclusive):

My guess is 332.699219
──────────────────────────────────── Your guess is too high.

──────── Try to guess my number  (it's between   328.796875   and   332.699219   inclusive):

My guess is 330.748047
──────────────────────────────────── Your guess is too high.

──────── Try to guess my number  (it's between   328.796875   and   330.748047   inclusive):

My guess is 329.772461
───────────────────────────────────── Your guess is too low.

──────── Try to guess my number  (it's between   329.772461   and   330.748047   inclusive):

My guess is 330.260254
───────────────────────────────────── Your guess is too low.

──────── Try to guess my number  (it's between   330.260254   and   330.748047   inclusive):

My guess is 330.504151
───────────────────────────────────── Your guess is too low.

──────── Try to guess my number  (it's between   330.504151   and   330.748047   inclusive):

My guess is 330.626099
──────────────────────────────────── Your guess is too high.

──────── Try to guess my number  (it's between   330.504151   and   330.626099   inclusive):

My guess is 330.565125
───────────────────────────────────── Your guess is too low.

──────── Try to guess my number  (it's between   330.565125   and   330.626099   inclusive):

My guess is 330.595612
───────────────────────────────────── Your guess is too low.

──────── Try to guess my number  (it's between   330.595612   and   330.626099   inclusive):

My guess is 330.610856
──────────────────────────────────── Your guess is too high.

──────── Try to guess my number  (it's between   330.595612   and   330.610856   inclusive):

My guess is 330.603234
──────────────────────────────────── Your guess is too high.

──────── Try to guess my number  (it's between   330.595612   and   330.603234   inclusive):

My guess is 330.599423
───────────────────────────────────── Your guess is too low.

──────── Try to guess my number  (it's between   330.599423   and   330.603234   inclusive):

My guess is 330.601329
──────────────────────────────────── Your guess is too high.

──────── Try to guess my number  (it's between   330.599423   and   330.601329   inclusive):

My guess is 330.600376
──────────────────────────────────── Your guess is too high.

──────── Try to guess my number  (it's between   330.599423   and   330.600376   inclusive):

My guess is 330.5999
───────────────────────────────────── Your guess is too low.

──────── Try to guess my number  (it's between   330.5999   and   330.600376   inclusive):

My guess is 330.600138
──────────────────────────────────── Your guess is too high.

──────── Try to guess my number  (it's between   330.5999   and   330.600138   inclusive):

My guess is 330.600019
──────────────────────────────────── Your guess is too high.

──────── Try to guess my number  (it's between   330.5999   and   330.600019   inclusive):

My guess is 330.59996
───────────────────────────────────── Your guess is too low.

──────── Try to guess my number  (it's between   330.59996   and   330.600019   inclusive):

My guess is 330.59999
───────────────────────────────────── Your guess is too low.

──────── Try to guess my number  (it's between   330.59999   and   330.600019   inclusive):

My guess is 330.600005
──────────────────────────────────── Your guess is too high.

──────── Try to guess my number  (it's between   330.59999   and   330.600005   inclusive):

My guess is 330.599998
───────────────────────────────────── Your guess is too low.

──────── Try to guess my number  (it's between   330.599998   and   330.600005   inclusive):

My guess is 330.600002
──────────────────────────────────── Your guess is too high.

──────── Try to guess my number  (it's between   330.599998   and   330.600002   inclusive):

My guess is 330.6

Congratulations!   You guessed the secret number in 29 tries.

Ring

<lang ring> min = 1 max = 100 see "think of a number between " + min + " and " + max + nl see "i will try to guess your number." + nl while true

     guess =floor((min + max) / 2) 
     see "my guess is " + guess + nl
     see "is it higher than, lower than or equal to your number " give answer
     ans = left(answer,1)
     switch ans
            on "l" min = guess + 1 
            on "h" max = guess - 1 
            on "e" exit 
            other see "sorry, i didn't understand your answer." + nl
     off

end see "goodbye." + nl </lang> Output:

think of a number between 1 and 100
i will try to guess your number.
my guess is 50
is it higher than, lower than or equal to your number l
my guess is 75
is it higher than, lower than or equal to your number h
my guess is 62
is it higher than, lower than or equal to your number h
my guess is 56
is it higher than, lower than or equal to your number l
my guess is 59
is it higher than, lower than or equal to your number l
my guess is 60
is it higher than, lower than or equal to your number e
goodbye.

Ruby

Computer plays versus itself <lang ruby>def play(low, high, turns=1)

 num = (low + high) / 2
 print "guessing #{num}\t"
 case is_it?(num)
 when 1
   puts "too high"
   play(low, num - 1, turns + 1)
 when -1
   puts "too low"
   play(num + 1, high, turns + 1)
 else
   puts "found the number in #{turns} turns."
 end

end

def is_it?(num)

 num <=> $number

end

low, high = 1, 100 $number = rand(low .. high)

puts "guess a number between #{low} and #{high}" play(low, high)</lang>

Example

guess a number between 1 and 100
guessing 50     too high
guessing 25     too low
guessing 37     too high
guessing 31     too high
guessing 28     too low
guessing 29     too low
guessing 30     found the number in 7 turns.

Since Ruby 2.0 it can be done actually using a built-in binary search (output as above): <lang ruby>r = (1..100) secret = rand(r) turns = 0

puts "Guess a number between #{r.min} and #{r.max}" r.bsearch do |guess| # bsearch works on ranges

 print "Guessing #{guess} \t"
 turns += 1
 low_high = secret <=> guess       # -1, 0, or 1
 puts ["found the number in #{turns} turns", "too low", "too high"][low_high]
 low_high

end </lang>

Rust

Works with: rustc version 1.0.0-nightly

<lang rust>use std::io::stdin;

const MIN: isize = 1; const MAX: isize = 100;

fn main() {

   loop {
       let mut min = MIN;
       let mut max = MAX;
       let mut num_guesses = 1;
       println!("Please think of a number between {} and {}", min, max);
       loop {
           let guess = (min + max) / 2;
           println!("Is it {}?", guess);
           println!("(type h if my guess is too high, l if too low, e if equal and q to quit)");
           let mut line = String::new();
           stdin().read_line(&mut line).unwrap();
           match Some(line.chars().next().unwrap().to_uppercase().next().unwrap()) {
               Some('H') => {
                   max = guess - 1;
                   num_guesses += 1;
               },
               Some('L')=> {
                   min = guess + 1;
                   num_guesses += 1;
               },
               Some('E') => {
                   if num_guesses == 1 {
                       println!("\n*** That was easy! Got it in one guess! ***\n");
                   } else {
                       println!("\n*** I knew it! Got it in only {} guesses! ***\n", num_guesses);
                   }
                   break;
               },
               Some('Q') => return,
               _ => println!("Sorry, I didn't quite get that. Please try again.")
           }
       }
   }

}</lang>

Scala

<lang Scala>object GuessNumber extends App {

 val n = 1 + scala.util.Random.nextInt(20)
 println("Guess which number I've chosen in the range 1 to 20\n")
 do println("Your guess, please: ")
 while (io.StdIn.readInt() match {
   case `n` => println("Correct, well guessed!"); false
   case guess if (n + 1 to 20).contains(guess) => println("Your guess is higher than the chosen number, try again"); true
   case guess if (1 until n).contains(guess) => println("Your guess is lower than the chosen number, try again"); true
   case _ => println("Your guess is inappropriate, try again"); true
 })

}</lang>

Scheme

Works with: Guile

<lang scheme>(define minimum 1) (define maximum 100)

(display "Enter a number from ")(display minimum) (display " to ")(display maximum)(display ": ") (define number (read))

(define input "")

(do ((guess (round (/ (+ maximum minimum) 2)) (round (/ (+ maximum minimum) 2))))

               ((string= input "="))
       (display "Is it ")(display guess)(display "?\n(h/l/=) > ")
       (set! input (symbol->string (read)))
       (if (string= input "h") (begin (display "OK...")
               (set! maximum (- guess 1))))
       (if (string= input "l") (begin (display "OK...")
               (set! minimum (+ guess 1)))))

(display "I was RIGHT!\n")</lang>

Seed7

The program reads the possible commands (l, h, c, q) as single keypresses from the KEYBOARD with getc. It is also possible to quit the program with q. The program recognices also a situation when there is only one possible number left and the command is not c.

<lang seed7>$ include "seed7_05.s7i"; $ include "keybd.s7i";

const proc: main is func

 local
   var boolean: okay is FALSE;
   var boolean: quit is FALSE;
   var integer: low is 1;
   var integer: high is 1000;
   var integer: guess is 0;
   var char: command is ' ';
 begin
   writeln("Choose a number between 1 and 1000.");
   write("Press Enter and I will start to guess the number.");
   readln;
   repeat
     guess := low + (high - low) div 2;
     write("My guess is: " <& guess);
     write(". How did I score (l=too low, h=too high, c=correct, q=quit)? ");
     flush(OUT);
     repeat
       command := lower(getc(KEYBOARD));
     until command in {'l', 'h', 'c', 'q'};
     writeln(command);
     case command of
       when {'l'}: low := succ(guess);
       when {'h'}: high := pred(guess);
       when {'c'}: okay := TRUE;
       when {'q'}: quit := TRUE;
     end case;
   until quit or okay or low > high;
   if not quit then
     writeln("So the number is: " <& guess);
     if low > high then
       writeln("Why did you cheat?");
     end if;
   end if;
   writeln("It was nice to play with you.");
 end func;</lang>

Example

Choose a number between 1 and 1000.
Press Enter and I will start to guess the number.
My guess is: 500. How did I score (l=too low, h=too high, c=correct, q=quit)? h
My guess is: 250. How did I score (l=too low, h=too high, c=correct, q=quit)? l
My guess is: 375. How did I score (l=too low, h=too high, c=correct, q=quit)? h
My guess is: 312. How did I score (l=too low, h=too high, c=correct, q=quit)? l
My guess is: 343. How did I score (l=too low, h=too high, c=correct, q=quit)? l
My guess is: 359. How did I score (l=too low, h=too high, c=correct, q=quit)? l
My guess is: 367. How did I score (l=too low, h=too high, c=correct, q=quit)? h
My guess is: 363. How did I score (l=too low, h=too high, c=correct, q=quit)? l
My guess is: 365. How did I score (l=too low, h=too high, c=correct, q=quit)? c
So the number is: 365
It was nice to play with you.

Sidef

<lang ruby>var min = 1 var max = 99 var tries = 0 var guess = pick(min..max)   print <<"EOT".chomp \n=>> Think of a number between #{min} and #{max} and I'll guess it!\n Press <ENTER> when are you ready... EOT   STDIN.readline   loop {

   print <<-EOT.chomp
   \n=>> My guess is: #{guess} Is your number higher, lower, or equal? (h/l/e)
   >#{' '}
   EOT

 

   ++tries
   given (STDIN.readline) {
       case (max <= min) {
           say "\nI give up..."
           break
       }
       when (/^h/i) {
           min = guess+1
       }
       when (/^l/i) {
           max = guess
       }
       when (/^e/i) {
           say "\nI knew it! It took me only #{tries} tries."
           break
       }
       default {
           say "error: invalid score"
           next
       }
   }

 

   guess = ((min+max) // 2)

}</lang>

Smalltalk

Works with: Pharo version 1.4

Create a class like this:

<lang smalltalk>Object subclass: #NumberGuesser

   instanceVariableNames: 
   classVariableNames: 
   poolDictionaries: 
   category: 'Rosettacode'

</lang>

Enter these methods into it:

<lang smalltalk>playBetween: low and: high

   Transcript clear.
   number := (low to: high) atRandom.
   self playBetween: low and: high atTurn: 1.
   

playBetween: low and: high atTurn: turn

   | guess |
   guess := (low + ((high - low) / 2)) asInteger.
   self showGuessing: guess atTurn: turn.
   true caseOf: { 
       [number > guess] -> 
           [self showNumberBeing: #low. self playBetween: guess and: high atTurn: turn+1 ].
       [number < guess] -> 
           [self showNumberBeing: #high. self playBetween: low and: guess atTurn: turn+1 ].
       [true] -> 
           [self showNumberFoundAtTurnNr: turn ] }.

showGuessing: guess atTurn: turn

   Transcript show: ('{1}. guessing: {2}' format: {turn asString. guess asString}).
   

showNumberBeing: comparisonToken

   Transcript show: ' ==> too ', (comparisonToken asString); cr.

showNumberFoundAtTurnNr: turn

   Transcript show: (' ==> found the number in {1} turn(s).' format: {turn asString}); cr.

</lang>

If you'd rather not use caseOf: you can write playBetween:and:atTurn: like this:

<lang smalltalk> playBetween: low and: high atTurn: turn

   | guess |
   guess := (low + ((high - low) / 2)) asInteger.
   self showGuessing: guess atTurn: turn.
   (guess = number)
       ifTrue: [self showNumberFoundAtTurnNr: turn ]
       ifFalse: [
         (number > guess)
             ifTrue: [self showNumberBeing: #low. self playBetween: guess and: high  atTurn: turn+1 ] 
             ifFalse: [self showNumberBeing: #high. self playBetween: low and: guess  atTurn: turn+1]].

</lang>

And evaluate this in a Workspace:

<lang smalltalk>g := NumberGuesser new. g playBetween: 1 and: 100. </lang>

Sample output:

1. guessing: 50 ==> too low
2. guessing: 75 ==> too low
3. guessing: 87 ==> too high
4. guessing: 81 ==> too low
5. guessing: 84 ==> too low
6. guessing: 85 ==> found the number in 6 turn(s).

Standard ML

A clever solution that uses the built-in binary search functions with a virtual list.

Works with: SML/NJ
Translation of: Go

<lang sml>structure GuessNumberHelper : MONO_ARRAY = struct

 type elem = order
 type array = int * int
 fun length (lo, hi) = hi - lo
 fun sub ((lo, hi), i) =
   let
     val n = lo + i
   in
     print ("My guess is: " ^ Int.toString (lo+i) ^ ". Is it too high, too low, or correct? (H/L/C) ");
     let
       val str = valOf (TextIO.inputLine TextIO.stdIn)
     in
       case Char.toLower (String.sub (str, 0)) of
         #"l" => GREATER
       | #"h" => LESS
       | #"c" => EQUAL
     end
   end
 (* dummy implementations for not-needed functions *)
 type vector = unit
 val maxLen = Array.maxLen
 fun update _ = raise Domain
 fun array _ = raise Domain
 fun fromList _ = raise Domain
 fun tabulate _ = raise Domain
 fun vector _ = raise Domain
 fun copy _ = raise Domain
 fun copyVec _ = raise Domain
 fun appi _ = raise Domain
 fun app _ = raise Domain
 fun modifyi _ = raise Domain
 fun modify _ = raise Domain
 fun foldli _ = raise Domain
 fun foldl _ = raise Domain
 fun foldri _ = raise Domain
 fun foldr _ = raise Domain
 fun findi _ = raise Domain
 fun find _ = raise Domain
 fun exists _ = raise Domain
 fun all _ = raise Domain
 fun collate _ = raise Domain

end

structure GuessNumberBSearch = BSearchFn (GuessNumberHelper)

val lower = 0 val upper = 100;

print ("Instructions:\n" ^

      "Think of integer number from " ^ Int.toString lower ^
      " (inclusive) to " ^ Int.toString upper ^ " (exclusive) and\n" ^
      "I will guess it. After each guess, you respond with L, H, or C depending\n" ^
      "on if my guess was too low, too high, or correct.\n");

case GuessNumberBSearch.bsearch (fn (_, x) => x) ((), (lower, upper)) of

 NONE => print "That is impossible.\n"

| SOME (result, _) => print ("Your number is " ^ Int.toString result ^ ".\n")</lang>

Swift

<lang>import Cocoa

var found = false let fh = NSFileHandle.fileHandleWithStandardInput() println("Enter an integer between 1 and 100 for me to guess: ") let data = fh.availableData var num:Int! var low = 0.0 var high = 100.0 var lastGuess:Double!


if let numFromData = NSString(data: data, encoding: NSUTF8StringEncoding)?.intValue {

   num = Int(numFromData)

}

func guess() -> Double? {

   if (high - low == 1) {
       println("I can't guess it. I think you cheated.");
       return nil
   }
   
   return floor((low + high) / 2)

}

while (!found) {

   if let guess = guess() {
       lastGuess = guess
   } else {
       break
   }
   println("My guess is: \(Int(lastGuess))")
   println("How was my guess? Enter \"higher\" if it was higher, \"lower\" if it was lower, and \"correct\" if I got it")
   let data = fh.availableData
   let str = NSString(data: data, encoding: NSUTF8StringEncoding)
   if (str == nil) {
       continue
   }
   if (str! == "correct\n") {
       found = true
       println("I did it!")
   } else if (str! == "higher\n") {
       low = lastGuess
   } else if (str! == "lower\n") {
       high = lastGuess
   }

}</lang>

Output:
Enter an integer between 1 and 100 for me to guess: 
10
My guess is: 50
How was my guess? Enter "higher" if it was higher, "lower" if it was lower, and "correct" if I got it
lower
My guess is: 25
How was my guess? Enter "higher" if it was higher, "lower" if it was lower, and "correct" if I got it
lower
My guess is: 12
How was my guess? Enter "higher" if it was higher, "lower" if it was lower, and "correct" if I got it
lower
My guess is: 6
How was my guess? Enter "higher" if it was higher, "lower" if it was lower, and "correct" if I got it
higher
My guess is: 9
How was my guess? Enter "higher" if it was higher, "lower" if it was lower, and "correct" if I got it
higher
My guess is: 10
How was my guess? Enter "higher" if it was higher, "lower" if it was lower, and "correct" if I got it
correct
I did it!
Program ended with exit code: 0

Tcl

<lang tcl>set from 1 set to 10 fconfigure stdout -buffering none while 1 {

   set guess [expr {($from+$to) / 2}]
   puts -nonewline "Guess: $guess\tWas it lower (<) equal (=) or higher (>)? "
   switch -- [gets stdin] {

< { set from [expr {$guess + 1}] } > { set to [expr {$guess - 1}] } = { puts "Found it: $guess" break } default { puts "What sort of a response was that?!" }

   }
   if {$to < $from} {

puts "No answer possible?!" break

   }

}</lang> Sample run:

Guess: 5	Was it lower (<) equal (=) or higher (>)? <
Guess: 8	Was it lower (<) equal (=) or higher (>)? >
Guess: 6	Was it lower (<) equal (=) or higher (>)? =
Found it: 6

UNIX Shell

Works with: bash

<lang bash>read -p "Lower bound: " lower read -p "Upper bound: " upper moves=0 PS3="> " while :; do

   ((moves++))
   guess=$(( lower + (upper-lower)/2 ))
   echo "Is it $guess?"
   select ans in "too small" "too big" "got it!"; do
       case $ans in
           "got it!")   break 2 ;;
           "too big")   upper=$(( upper==guess ? upper-1 : guess )); break ;;
           "too small") lower=$(( lower==guess ? lower+1 : guess )); break ;;
       esac
   done
   ((lower>upper)) && echo "you must be cheating!"

done echo "I guessed it in $moves guesses"</lang>

VBA

<lang vba> Sub GuessNumberPlayer() Dim iGuess As Integer, iLow As Integer, iHigh As Integer, iCount As Integer Dim vSolved As Variant On Error GoTo ErrHandler MsgBox "Pick a number between 1 and 100. I will guess it!", vbInformation + vbOKOnly, "Rosetta Code | Guess the Number Player" iCount = 0 iLow = 1 iHigh = 100 Do While Not vSolved = "Y"

   iGuess = Application.WorksheetFunction.RandBetween(iLow, iHigh)
   iCount = iCount + 1

CheckGuess:

   vSolved = InputBox("My guess: " & iGuess & vbCr & vbCr & "Y = Yes, correct guess" & vbCr & _
       "H = your number is higher" & vbCr & "L = your number is lower" & vbCr & "X = exit game", "Rosetta Code | Guess the Number Player | Guess " & iCount)
   Select Case vSolved
       Case "Y", "y":              GoTo CorrectGuess
       Case "X", "x":              Exit Sub
       Case "H", "h":              iLow = iGuess + 1
       Case "L", "l":              iHigh = iGuess - 1
       Case Else:                  GoTo CheckGuess
   End Select

Loop CorrectGuess:

   MsgBox "I guessed number " & iGuess & " in just " & iCount & " attempts!", vbExclamation + vbOKOnly, "Rosetta Code | Guess the Number Player"
   Exit Sub

ErrHandler:

   MsgBox "Not possible. Were you cheating?!", vbCritical + vbOKOnly, "Rosetta Code | Guess the Number Player | ERROR!"

End Sub </lang>

Wren

Translation of: Kotlin
Library: Wren-str

<lang ecmascript>import "io" for Stdin, Stdout import "/str" for Char

var hle var lowest = 1 var highest = 20 var guess = 10 System.print("Please choose a number between 1 and 20 but don't tell me what it is yet\n")

while (true) {

   System.print("My guess is %(guess)")
   while (true) {
       System.write("Is this higher/lower than or equal to your chosen number h/l/e : ")
       Stdout.flush()
       hle = Char.lower(Stdin.readLine())
       if (hle == "l" && guess == highest) {
           System.print("It can't be more than %(highest), try again") 
           hle = "i" // signifies invalid
       } else if (hle == "h" && guess == lowest) {
           System.print("It can't be less than %(lowest), try again")
           hle  = "i"
       }
       if ("hle".contains(hle)) break
   }
   if (hle == "e") {
       System.print("Good, thanks for playing the game with me!")
       break
   }
   if (hle == "h") {
       if (highest > guess - 1) highest = guess - 1
   } else {
       if (lowest < guess + 1) lowest = guess + 1
   }
   guess = ((lowest + highest)/2).floor

}</lang>

Output:

Sample session (player chooses 12):

Please choose a number between 1 and 20 but don't tell me what it is yet

My guess is 10
Is this higher/lower than or equal to your chosen number h/l/e : l
My guess is 15
Is this higher/lower than or equal to your chosen number h/l/e : h
My guess is 12
Is this higher/lower than or equal to your chosen number h/l/e : e
Good, thanks for playing the game with me!

XPL0

<lang XPL0>include c:\cxpl\codes; \intrinsic 'code' declarations int Hi, Lo, Guess; [Text(0, "Think of a number between 1 and 100 then press a key."); if ChIn(1) then []; Lo:= 1; Hi:= 101; loop [Guess:= (Lo+Hi)/2;

       Text(0, "^M^JIs it ");  IntOut(0, Guess);
       Text(0, " (Y = yes, H = too high, L = too low)? ");
       case ChIn(1) of
         ^L,^l: Lo:= Guess;
         ^H,^h: Hi:= Guess;
         ^Y,^y: quit
       other   ChOut(0, 7\bel\);
       ];

Text(0, "^M^JYippee!"); ]</lang>

Example output:

Think of a number between 1 and 100 then press a key.
Is it 51 (Y = yes, H = too high, L = too low)? H
Is it 26 (Y = yes, H = too high, L = too low)? H
Is it 13 (Y = yes, H = too high, L = too low)? L
Is it 19 (Y = yes, H = too high, L = too low)? H
Is it 16 (Y = yes, H = too high, L = too low)? L
Is it 17 (Y = yes, H = too high, L = too low)? Y
Yippee!

zkl

Your basic binary search. <lang zkl>println("Pick a number between 0 and 100 and remember it."); low,high,g := 0,100, 20; while(True){

  r:=ask("I guess %d; is that high, low or =? ".fmt(g)).strip().toLower();
  if(r=="="){ println("Yea!"); break; }
  if(r[0]=="h") high=g-1 else low=g+1;
  if(low==high){ println("Yea! the number is ",low); break; }
  if(low>high){ println("I'm confused!"); break; }
  g=(low + high)/2;

}</lang>

Output:
Pick a number between 0 and 100 and remember it.
I guess 20; is that high, low or =? l
I guess 60; is that high, low or =? h
I guess 40; is that high, low or =? h
I guess 30; is that high, low or =? h
I guess 25; is that high, low or =? l
I guess 27; is that high, low or =? h
Yea! the number is 26

ZX Spectrum Basic

Translation of: BBC_BASIC

<lang zxbasic>10 LET min=1: LET max=100 20 PRINT "Think of a number between ";min;" and ";max 30 PRINT "I will try to guess your number." 40 LET guess=INT ((min+max)/2) 50 PRINT "My guess is ";guess 60 INPUT "Is it higuer than, lower than or equal to your number? ";a$ 65 LET a$=a$(1) 70 IF a$="L" OR a$="l" THEN LET min=guess+1: GO TO 40 80 IF a$="H" OR a$="h" THEN LET max=guess-1: GO TO 40 90 IF a$="E" OR a$="e" THEN PRINT "Goodbye.": STOP 100 PRINT "Sorry, I didn't understand your answer.": GO TO 60</lang>