How do I make a randomized test on Matlab?

Below is my code. I am trying to have matlab give me a random question and then it tell me if I am right or wrong based on my answer. As you can see I am typing in units and it keeps saying that kg, m, and s are unrecognizable functions. Here is my code.

QandA={'what is metric units for Acceleration? ', 'm/s^2';
    'what is metric units for Density? ', 'kg/m^3';
    'what is metric units for Energy,Heat,Work? ', '(kg*m^2)/s^2';  
    'what is metric units for Force? ', '(kg*m)/s^2';
    'what is metric units for Length? ', 'm';
    'what is metric units for Mass? ', 'kg'; 
    'what is metric units for Power? ', '(kg*m^2)/s^3';
    'what is metric units for Pressure? ', 'kg/(m*s^2)';
    'what is metric units for Temperature? ' 'K';
    'what is metric units for Time? ', 's';
    'what is metric units for Volume? ', 'm^3';};

qorder = randperm(numel(QandA(:,1)));
QandAreordered = QandA(qorder, :);
for qidx=1:size(QandAreordered, 1)
    answer=input(QandAreordered{qidx, 1}); %double
    if (answer == str2double(QandAreordered{qidx, 2})) %string to double
        fprintf('Correct\n', '%s');
    else 
        fprintf('Incorrect\n', '%s'); 
    end
end

Please help me ASAP if possible. I am using this to study for an Exam I have next week.

[Voss]

The '%s' in those fprintf calls is unnecessary because it's ignored by fprintf since the first argument (e.g., 'Correct\n') has no formatting operators.

fprintf('Correct\n') % this is sufficient

Correct

Answer 1

[Voss]

Use the 's' option in input to capture what the user types as a character array (as opposed to evaluating it), and use strcmp instead of == to compare the user's answer with the correct answer.

QandA={'what is metric units for Acceleration? ', 'm/s^2';
       'what is metric units for Density? ', 'kg/m^3';
       'what is metric units for Energy,Heat,Work? ', '(kg*m^2)/s^2';  
       'what is metric units for Force? ', '(kg*m)/s^2';
       'what is metric units for Length? ', 'm';
       'what is metric units for Mass? ', 'kg'; 
       'what is metric units for Power? ', '(kg*m^2)/s^3';
       'what is metric units for Pressure? ', 'kg/(m*s^2)';
       'what is metric units for Temperature? ' 'K';
       'what is metric units for Time? ', 's';
       'what is metric units for Volume? ', 'm^3';};
    
qorder = randperm(numel(QandA(:,1)));
QandAreordered = QandA(qorder, :);
for qidx=1:size(QandAreordered, 1)
    answer=input(QandAreordered{qidx, 1},'s'); % char
    if strcmp(answer,QandAreordered{qidx, 2}) % string (or char) comparison
       fprintf('Correct\n');
    else 
       fprintf('Incorrect\n'); 
    end
end

[Brett Nelson]

It works perfect now! Thank you so much for your help and quick response!

[Voss]

You're welcome! Any questions, let me know.