How do I stop an input from being entered twice?

I'm working on a game of hangman for matlab, I am unsure how to stop the same input from being entered twice or stop it increasing the count for correct index.

My code is:

words=readWords('dictionary_long.txt');

wordNum= rand(1,1);
wordNum=9887*wordNum;
wordNum=ceil(wordNum);
guessingWord=words(wordNum);

guessingWord=char(guessingWord);

while length(guessingWord)<=4
    wordNum= rand(1,1);
    wordNum=9887*wordNum;
    wordNum=ceil(wordNum);
    guessingWord=words(wordNum);
    guessingWord=char(guessingWord);
end


Guess = [];
UserGuess=[];
incorrectCount=0;
lettersLeft=length(guessingWord);
guessesLeft=8;
guessCount=0;
correctCount=0;

for i=1:length(guessingWord)
    Guess=[Guess '_'];
end

Guess1=input('Please enter your first guess: ', 's');
for i=1:length(Guess)
    if Guess1==guessingWord(i)
        Guess(i)=Guess1;
        lettersLeft=lettersLeft-1;
        
        correctCount=correctCount+1;       
    else
        incorrectCount=incorrectCount+1;
    end
end

if incorrectCount==length(guessingWord);
    guessesLeft=guessesLeft-1;
    fprintf('Your letter is not in the word!\n');
else
    fprintf('You have made a correct guess!\n')
end


disp(Guess);

NewGuess=0;





while ~(guessesLeft <= 0) || ~(correctCount == length(guessingWord-1))
    incorrectCount1=0;
    currentNum=0;
    NewGuess=input('Please enter your guess: ','s');
    for i=1:length(Guess)
        if NewGuess==guessingWord(i)
            Guess(i)=NewGuess;
            lettersLeft=lettersLeft-1;
            currentNum=currentNum+1;
            
            correctCount=correctCount+1;       
        else
            incorrectCount1=incorrectCount1+1;
        end
    end
    
    if currentNum==0
        fprintf('Your letter is not in the word!\n');
        guessesLeft=guessesLeft-1;
    else
        fprintf('You have made a correct guess!\n');
    end
    disp(Guess);
    
end

if guessesLeft==0
    fprintf('You didnt win! Not all letters were guessed.\n');
else
    fprintf('You won! You correctly guessed all the letters!\n');
end

Answer 1

[Manas]

Hello Matthew Smyth,

I understand that you want to develop a MATLAB program that can simulate the game of hangman. Particularly, you are facing an issue preventing the same input from being entered twice or stopping the correct-guesses counter from incrementing again for an already verified input.

After inspecting your code, I identified a few areas in the code that can be modified.

• This if-else block will always execute the else block as the condition can never be true.

            if incorrectCount==length(guessingWord);
                guessesLeft=guessesLeft-1;
                fprintf('Your letter is not in the word!\n');
            else
                fprintf('You have made a correct guess!\n')
            end

• Consider combining the first guess prompt with the while loop to make the code look cleaner easier to understand.
• The looping conditions seem to be incorrect.
• The second half of the while condition seems to be incorrect even according to your current logic

            while ~(guessesLeft <= 0) || ~(correctCount == length(guessingWord-1))

Coming back to the main issue of mitigating the incrementation of the "correctCount" counter for the same input, a truth-table (boolean array) can be considered. Initially a truth-table of size "guessingWord" could be initialized with all indexes set as false. Once a correct guess is made, that index can be flipped to true so that correctCount" counter is not updated again for that particular guess.

Here is a sample implementation that combines all of the above suggestions

IsGuessed = false(1, length(guessingWord))
while ~(guessesLeft <= 0) || ~(correctCount == length(guessingWord))
    incorrectCount=0;
    UserGuess=input('Please enter your guess: ','s');
    for i=1:length(guessingWord)
        if (UserGuess==guessingWord(i) && IsGuessed(i) == false)
            Guess(i)=UserGuess;
            lettersLeft=lettersLeft-1;
            correctCount=correctCount+1;       
        else
            incorrectCount=incorrectCount+1;
        end
    end
    
    if incorrectCount==1
        fprintf('Your letter is not in the word!\n');
        guessesLeft=guessesLeft-1;
    else
        fprintf('You have made a correct guess!\n');
    end
    disp(Guess);
end

Again, this is only a sample implementation. Please feel free to make changes to it as per your requirements.

Hope this helps!