Why does this give me the "Unable to perform assignment because the left and right sides have a different number of elements." error?

Hi,

I'm trying to convert my code into an app as an exercise. I'm trying to get a list to update its items to contain all components.

function CreateComponentButtonPushed(app, event)
            new_comp = comp(app.ComponentNameEditField.Value, length(app.components)+1, app.MolarMassgmolEditField.Value);
            new_comp.setAntoine([app.AntoineEqnAEditField.Value, app.AntoineEqnBEditField.Value, app.AntoineEqnCEditField.Value]);
            app.components = [app.components, new_comp];
            display_names = zeros(length(app.components), 1);
            for i = 1:length(display_names)
                %Set the current value to the name of the component
                display_names(i) = app.components(i).name;
            end
            disp(display_names);
            
            %Supposed to change the list in the app to contain all the new
            %display names
            app.ComponentsListBox.Items = display_names;
end

This is throwing up an error in the display_names(i) = app.components(i).name line. What's the issue here?

Thanks in advance.

Answer 1

[Harsh Saxena]

Hi,

Maybe this error is occuring due to the fact that app.components.name(i) is a character array, so MATLAB considers left hand side as a double value while the right hand side as an array of characters. Try initializing the display_names as:

display_names = strings([length(app.components), 1]);

Hope this helps!

Answer 2

[Image Analyst]

Perhaps make it a cell array:

numControls = length(app.components)
display_names = cell(numControls, 1);
for k = 1 : numControls % Don't use i as an iterator.
    % Set the current value to the name of the component
    display_names{k} = app.components(k).name; % Use braces, not parentheses.
end

See the FAQ:

https://matlab.fandom.com/wiki/FAQ#What_is_a_cell_array?

If you have any more questions, then attach your .mlapp file, and any data needed at run time, with the paperclip icon after you read this:

TUTORIAL: How to ask a question (on Answers) and get a fast answer