**⚠️ Warning: This is a draft ⚠️**

This means it might contain formatting issues, incorrect code, conceptual problems, or other severe issues.

If you want to help to improve and eventually enable this page, please fork RosettaGit's repository and open a merge request on GitHub.

{{task|Games}}

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

- [[Guess the number/With Feedback]]
- [[Bulls and cows/Player]]

## 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;
```

## ALGOL 68

{{works with|ALGOL 68G|Any - tested with release 2.8.3.win32}}

```
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
```

## 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

## AutoHotkey

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

```
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"
}
```

## BBC BASIC

```
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
```

## Batch File

```
@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
```

{{out}}

```
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
```

## 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; }

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.
{{trans|Java}}

#include <stdio.h> #include <stdlib.h> #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. #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; }

## 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.
{{trans|Go}}

#include <iostream> #include <algorithm> #include <string> #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; }

## C#

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(); } } }

## 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");
}
}
}
}
```

## 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)))))

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:

(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!"))))

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):

(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)))

## D

{{trans|Python}}

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."); }

{{out}}

```
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.
```

## Elixir

{{works with|Elixir|1.2}}

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)

{{out|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

% 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.

{{out}}

```
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

{{trans|PureBasic}}

```
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
```

## 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")
}
}
}
}
```

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!
```

## Fortran

{{works with|Fortran|95 and later}}

```
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
```

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

```
' 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
```

Sample input/output {{out}}

```
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.[http://golang.org/pkg/sort/#Search]

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) }

Manual solution:

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") } } }

## Haskell

Explicit version with arbitrary range:

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

Short version with set limits:

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!"

=={{header|Icon}} and {{header|Unicon}}== {{trans|Fantom}}

```
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
```

=={{header|IS-BASIC}}==

```
## J
```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.
)
```

Example session:

```
This could be made more efficient by replacing <code>guess=.lo+?hi-lo</code> with <code>guess=.<.-:lo+hi</code>. (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.
{{trans|Go}}
```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);
}
}
```

## 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 LOG_{2} of the range. That's not true if the user changes his number, but then he gets what he deserves.

#!/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();

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 $\backslash left\backslash lceil-\backslash log\backslash left(\backslash frac\{1\}\{\backslash mathrm\{upper\}\; -\; \backslash mathrm\{lower\}\}\backslash right)\; /\; \backslash log(2)\backslash right\backslash rceil$ to calculate the maximum number of guesses it will need.

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.")

## Kotlin

{{trans|FreeBASIC}}

// 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 } }

Sample input/output: {{out}}

```
<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>
## Lasso
```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? ')
}
}
}
```

Examples:

```
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

```
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."
```

## Lua

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

```
## MATLAB
```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
```

{{out}}

```
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.
```

=={{header|Mathematica}} / {{header|Wolfram Language}}==

```
## MAXScript
```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.")
)
)
```

{{out}}

```
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
```

=={{header|Modula-2}}==

```
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.
```

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

import rdstdin, 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 let txt = readLineFromStdin("Guess $# is: $#. The score for which is (h,l,=): " .format(i, guess)) 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."

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.
```

=={{header|Objective-C}}== A clever solution that uses the built-in binary search functions with a virtual list. {{trans|Java}}

```
@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
#define LOWER 0
#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;
}
```

## PARI/GP

```
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()
)
)
)
);
}
```

## 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.

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

#!/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); }

```
=>> 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.
```

## Perl 6

```
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?!?!?";
}
```

You may execute this program with '`perl6 program`' or with '`perl6 program min max`'. Perl 6 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.

## Phix

```
integer Min=0, Max=100, Guess, Response
printf(1,"Think of a number between %d and %d.\n",{Min,Max})
while 1 do
Guess = floor((Max+Min)/2)
printf(1,"My guess is %d, is this too high, too low, or correct? (H/L/C)", Guess)
Response = lower(wait_key())
puts(1,"\n")
if Response='h' then
Max = Guess-1
elsif Response='l' then
Min = Guess+1
elsif Response='c' then
puts(1,"I did it!\n")
exit
else
puts(1,"I do not understand that...\n")
end if
if Max<Min then
puts(1,"I think something is strange here...\n")
exit
end if
end while
```

## PicoLisp

{{trans|PureBasic}}

```
(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...")) ) ) ) ) )
```

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

```
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).
```

Example:

```
?- 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
```

## 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
```

## 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.")

'''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.
{{trans|Go}}

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)

;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.
```

## 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))
```

Another way with loops and mutation

```
#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!"))
```

## REXX

### with positive integers

This version only handles positive integers up to the nine decimal digits, but the default HIGH is one thousand.

```
/*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."
```

'''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. ```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."" ``` '''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 ```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 ``` Output: ```txt 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 ```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) ``` Example ```txt 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): ```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 ``` ## Rust {{works with|rustc|1.0.0-nightly}} ```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.") } } } } ``` ## Scala ```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 }) } ``` ## Scheme {{works with|Guile}} ```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") ``` ## Seed7 The program reads the possible commands (l, h, c, q) as single keypresses from the [http://seed7.sourceforge.net/libraries/keybd.htm#KEYBOARD KEYBOARD] with [http://seed7.sourceforge.net/libraries/keybd.htm#getc%28in_console_keybd_file%29 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. ```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; ``` Example ```txt 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 ```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 Presswhen 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) } ``` ## Smalltalk {{works with|Pharo|1.4}} Create a class like this: ```smalltalk Object subclass: #NumberGuesser instanceVariableNames: '' classVariableNames: '' poolDictionaries: '' category: 'Rosettacode' ``` Enter these methods into it: ```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. ``` If you'd rather not use `caseOf:`

you can write`playBetween:and:atTurn:`

like this: ```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]]. ``` And evaluate this in a Workspace: ```smalltalk g := NumberGuesser new. g playBetween: 1 and: 100. ``` Sample output: ```txt 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}} {{trans|Go}} ```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") ``` ## Swiftimport 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 } } ``` {{out}} ```txt 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 ```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 } } ``` Sample run: ```txt 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}} ```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" ``` ## VBA ```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 ``` ## XPL0 ```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!"); ] ``` Example output: ```txt 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. ```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; } ``` {{out}} ```txt 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 {{trans|BBC_BASIC}} ```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 ``` {{omit from|GUISS}} {{omit from|Lilypond}}