Choose a random button from a set of 9 arranged in a 3x3?

app.FirstNumber.Text = num2str(app.First_Number);
app.SecondNumber.Text = num2str(app.Second_Number);
app.Operator.Text = "+";

Answer = app.First_Number + app.Second_Number; % Operator needs to be able to change

n = randi(9);
app.Button_(n).Text = num2str(Answer); % Button needs to move to a random button_(1-9)

Essentially im trying to make a random button become the correct answer, but i keep getting an error message of Button_ is not a recodnized method or property.

Answer 1

[Voss]

Use this syntax:

button_name = sprintf('Button_%d',n);
app.(button_name).Text = num2str(Answer);

Reference: https://www.mathworks.com/help/matlab/matlab_prog/generate-field-names-from-variables.html

[Voss]

And to be able to change the operator, you can do something like this:

operator_lookup = { ...
    "+", @plus; ...
    "-", @minus; ...
    "*", @times; ... actually element-wise multiplication, .*
    "/", @rdivide; ... element-wise division, ./
    };

idx = find([operator_lookup{:,1}] == string(app.Operator.Text), 1);

if isempty(idx)
    error('Invalid operator')
end

Answer = operator_lookup{idx,2}(app.First_Number,app.Second_Number);

References:

https://www.mathworks.com/help/matlab/function-handles.html

https://www.mathworks.com/help/matlab/matlab_prog/matlab-operators-and-special-characters.html

https://www.mathworks.com/help/matlab/ref/times.html

https://www.mathworks.com/help/matlab/ref/rdivide.html