how can i store input characters from user and every time when get new input compare it with already stored values if present already then give error message?

I want to get input characters from user and store it in an array or any other storing elements in matlab, and while loop is running so every time when new character from user is get, it is first compared with the already stored characters, if present in the array already, an error message is generated. This input will be used in switch statement later.

Answer 1

[Jaynik]

Hi Samia,

You can follow two approaches here but the overall steps remain the same. We can initialize an empty data structure to store the characters. Then we obtain the input from the user using the input function. We check the data structure for the input and proceed with the code.

Approach 1: Using while loop and array as suggested by you

storedChars = [];
while true
    newChar = input('Enter a character: ', 's');
    
    % Check if the character is already in the array
    if any(storedChars == newChar)
        disp('Character already entered.');
    else
        % Add the new character to the array
        storedChars = [storedChars, newChar];
        
        switch newChar
            % Your code
        end
    end
end

Approach 2: Using isKey and container.Map

storedChars = containers.Map('KeyType', 'char', 'ValueType', 'logical');
while true
    newChar = input('Enter a character: ', 's');
    
    % Check if the character is already in the map
    if isKey(storedChars, newChar)
        disp('Character already entered.');
    else
        % Add the new character to the map
        storedChars(newChar) = true;
        
        switch newChar
            % Your code
        end
    end
end

Please refer the following documentation to read more about these:

• input: https://www.mathworks.com/help/matlab/ref/input.html
• containers.Map: https://www.mathworks.com/help/matlab/ref/containers.map.html
• isKey: https://www.mathworks.com/help/matlab/ref/containers.map.iskey.html

Hope this helps!