Giving a button a numeric value in app designer

I was trying to create a button that would add a numeric value to text area so far I can't seem to get it to work, my code so far is

       % Button pushed function: BananaButton
        function BananaButtonPushed(app, event)
            app.TotalCaloriesTextArea.Value = 
            [app.TotalCaloriesTextArea.Value{1} event.Source.Text];
            
          
           
        end
        end

[Walter Roberson]

            app.TotalCaloriesTextArea.Value = ...
                string(app.TotalCaloriesTextArea.Value{1}) + event.Source.Text;

Note that if you want a space between the number and the previous text then use + " " after the first part.

[Michael Clopton]

I appreciate the response, i'm trying to create a calorie counter app. I want each button to add the calories to a text area. I think I may be using the wrong codes.

[Walter Roberson]

It seems to me that you would want to test to see if the text area is empty, and if so initialize to 0 and otherwise pull out the text area value. (You are using app designer so I gather that text areas can be configured as numeric.) Then add the values, and write into the text area.

Something like

            app.TotalCaloriesTextArea.Value = ...
            app.TotalCaloriesTextArea.Value{1} + event.Source.Text;

or perhaps

            app.TotalCaloriesTextArea.Value = ...
            app.TotalCaloriesTextArea.Value{1} + str2double(event.Source.Text);