how do i make the user only input 1 letter at a time with this code?

play = menu("Play A Word Game? ","Yes","No");
cPLAY = 1;
while play == 0 && cPLAY < 5
    play = menu("Play A Word Game? ","Yes","No");
    cPLAY = CPLAY + 1;
end 
if play == 0
    error('TOO LATE')
end
while play == 1
    fprintf("Guess the 5 letter word: _____ \n\n")
    index = randi(495); %the bank of words I am using has 496 words
    wordstring= string(WORDS(index));
    WORD = char(WORDS(index)); % must use a character array,
    fprintf('A word has been chosen. Please click to continue.')
    pause()
    
    % Setup Correct and Wrong character strings (Task 2)
    wrong = 0;
    right = 0;
    while right < 5 && wrong < 9 
        clc
        correct = char("_____");
        badGuesses = '';
        disp(correct);
        fprintf("\n----- %d of 9 incorrect guesses: %s ------\n\n", wrong, string(badGuesses));
        GUESS = input("What is your guess? Please enter lowercase letters only:  \n", 's');
        GUESS = char(GUESS);
        % Check if the guess is correct or not (Task 3)
        anyRight = 0
        for x = 1:1:5
            if WORD(x) == GUESS
                correct(x) = GUESS;
                anyRight = 1;
                right = right + 1;
            end
        end
        if anyRight == 0 
            badGuesses = [badGuesses,GUESS];
            wrong = wrong + 1; 
        end
    end 

Answer 1

[Walter Roberson]

input() cannot be constrained to accept only single characters.

You could menu() or listdlg() listing the possible characters. As an enhancement, your list of possible characters could be changed to eliminate the characters that have already been chosen.