How do I use MATLAB app designer to display a command window for my app?

I am converting a program I wrote in regular scripts to an app. I want to be able to have a window in my app that I can write data to.

I have been trying to use

fprintf(object,"Some Text\n")

I have tried using the slrealtime System Log block but I cannot print to it.

I also tried writing to a file and then pulling that back into the app at the end of execution.

I need to print text to the app somehow. How should I be attacking this.

[Tom Coté]

If anyone has commentary on how I asked my question of wants more detail let me know, I am just a student in search of the knowledge to get through undergrad.

[Jan]

What is "object" in your fprintf command? An edit field is the standard to display and edit text.

[Tom Coté]

I tried using

fprintf(app.SystemLog,"Text");

And then I tried a different approach

lg = fopen('Log.txt','W')
fprintf(lg,"Text")

But then I could not get the text to display in my app

I'll give an edit field a shot

Answer 1

[Jan]

This is "gun-shot programming". Please read the documentation:

doc fprintf
doc fopen

Both commands do not write text to a GUI element. How did you create app.SystemLog?

Does your app.SystemLog has a property called "Value"? Try

app.SystemLog.Value = "Hello"

See: https://www.mathworks.com/help/matlab/ref/matlab.ui.control.editfield-properties.html

[Tom Coté]

Update

SystemLog is unique to simulink real-time it does not have property value, I was, admittedly foolishly, trying to shoehorn my command window output into this simulink real-time object.

I came up with a functional solution, albeit not vert elegant:

using a text box element named TextArea_2

defined as:

TextArea_2                   matlab.ui.control.TextArea

I added a property to store my strings, under public properties of my app class

outText = [];

I created this function:

%     APPLOGGER.m
%     Thomas Cote
%     Created: 03/16/22
%     Umass Lowell - EECE.2080 - Basic EE lab II
% 
%    handles text output for matlab app
% 

function AppLogger(app,string)
    app.outText = [app.outText; sprintf(string)];
    app.TextArea_2.Value = app.outText;
end

and I called this function as:

AppLogger(app,"Analyzing Data.....")

This has been working out for me. The peice I was missing was that I did not understand which app designer elements I should be using. a Text Area element worked much better than a System Log or an Edit Field.

Hope this helps :)

Also, I could not find a defintion for "Gun-Shot Programming" anywhere, would you mind explainging or linking me to a definition.

[Jan]

You find a list of anti patterns here: https://en.wikipedia.org/wiki/Anti-pattern

fprintf(app.SystemLog,"Text");

Here the shotgun style is to choose fprintf because the name sounds like something, which culd solve the problem. But takeing a look into the documentation reveals directly, that this is not matching.

Writing the text to a file andhoping tofind a method to insert the file's contents in a GUI element, is an XY-problem.

[Joseph Keogh]

Hey! I need to update a terminal UI element from guide to appdesigner. It includes a command box for user input. Do you have a way to allow for input?

[Joseph Keogh]

Preferably avoiding eval statements to avoid exploits in security

[Huy]

Hi Tom, just want to give you a credit for the simple solution that you have!

Thank you a lot!

Sincerely,

Huy