Can I execute MATLAB script that is written in Edit box in a GUI created by GUIDE?

Hi,

I created a GUI using GUIDE. I would like to allow the user to input MATLAB script in an Edit box. Then I execute the string inside the Edit box as a MATLAB script. Is this possible? Thanks in advance.

Answer 1

[Mohamed Abdelkader Zahana]

I think I found the answer, and have tested it successfully.

One can use:

eval(expression)

[Walter Roberson]

One cannot use that securely. And using it to make changes in the state of your program is really fragile. "poofing" variables into existence inevitably ends badly.

And are you at least using try/catch around the eval() to account for the pretty much 100% probability that someone will make a typing mistake and enter text that is not a valid command?

Answer 2

[Walter Roberson]

And when the user enters the text

!delete *.*

?

[Mohamed Abdelkader Zahana]

I can limit the execution to only a subset of commands!!

[Walter Roberson]

If you can limit the execution to a subset of commands, then you can parse the command line to extract parameters that you pass to your own routines instead of asking MATLAB to execute the code.

"Scrubbing" input before executing it is a persistent security problem. For example a bunch of web sites that thought they were securing strings just fine turned out to fail badly when UTF-8 encoding created new ways of inputting close-quotes and so allowed people to inject arbitrary commands onto sites. See also the history of "SQL Injection" hacks.

[Steven Lord]

And when you qualify your inputs incorrectly, incompletely, or not at all you can end up spending time with Bobby Tables.

[Tareq Rahmani]

Hi all

How can I save a whole MATLAB script in a string , then run that string without saving the script to any file ?

[Walter Roberson]

>> s = sprintf('disp("this is line 1");\ndisp("this is line 2")')

s =

    'disp("this is line 1");
     disp("this is line 2")'

>> eval(s)
this is line 1
this is line 2

We do not recommend using eval() however; there are many ways for it to go wrong. Such as if the user enters

!delete *.*

[Tareq Rahmani]

Thanks very much .

Now, I have this problem. The below is a function which is called on button pressed.

function ButtonPushed(app, event)
             x = app.TextArea.Value;
             str = regexprep(x,'\n',';');
             msgbox(str );
            %eval(str);
            % msgbox( sprintf('%f',a));
        end

In fact, I am reading from a textarea many lines like below :

x = [0:1]
y=sin(x)+cos(x)
plot(x,y)

and I want to make them one line (separated by ; ) like below :

x = [0:1];y=sin(x)+cos(x);plot(x,y)

I spent all the night and didn't get how ? Thanks for you.

[Walter Roberson]

The Value property from a text area does not have any \n characters. No matter how you initialize it, what is returned when you retrieve the Value is a cell array of character vectors.

For example,

function ButtonPushed(app, event)
             x = app.TextArea.Value;
             str = strjoin(strtrim(x), ';');
             msgbox(str );
            %eval(str);
            % msgbox( sprintf('%f',a));
        end

[Tareq Rahmani]

Thanks very much

Excellent !

[Tareq Rahmani]

Can I have your support .

what is wrong with the below : it shows me error :

function TeFlowButtonPushed(app, event)

x = app.TextArea.Value;

str = strjoin(strtrim(x), ';');

% msgbox(str );

%eval(str);

% msgbox( sprintf('%f',a));

x=strsplit(str,';');

for k = 1:length(x)

YourMatrix = [eval(x(k))];

table_as_cell = num2cell(YourMatrix);

table_handle = app.UITable;

set(table_handle, 'Data', table_as_cell);

end

end

it shows error: Error using eval Must be a string scalar or character vector

[Tareq Rahmani]

what is wrong here

[Walter Roberson]

The text you are eval includes an = assignment. You cannot assign the output of such statements: it would be like having the line

Matx = x = 7

You can only assign the output of eval when it computes a value without assignment.

See also evalc()

[Tareq Rahmani]

Hi Walter ,

I hope you are fine. Thanks for answers. I have this script :

 str = '';
            x = app.TextArea.Value;
            str = strjoin(strtrim(x), ';');
            % msgbox(str );
            %eval(str);
            % msgbox( sprintf('%f',a));
            %x=strsplit(str,';');
            %YourMatrix = [eval(str)];
            %YourMatrix = [evalin('base',(str))];
            %table_as_cell = num2cell([eval(str)]);
            table_handle = app.UITable;
            
             set(table_handle, 'Data', num2cell([evalc(str)]) );   % set(table_handle, 'Data', num2cell([evalc(str)]));
           

and it gives me this below output in table : I don't want that the words splitted into cells where each letter in one cell. I want that whole word be in one cell !

If you look the ans is splitted into a n s in different columns !

[Walter Roberson]

evalc() captures as text, not as number. There is no guarantee that the string evaluated only outputs numbers. Indeed, since it does not have terminating semicolon, it outputs

x =

     2


y =

     3


ans =

          2.23606797749979

and it is not clear what exactly you would want your Data to be set to in that case.

If you put in the terminating semi-colons on every line, and if you can be sure that they did not use an assignment statement for the last expression, such as if you ask to execute 'x=2; y=3; sqrt(x+y);' then you can eval() the string and use ans . But can you be sure that the user will not ask for

          x=2
          y=3
          z=sqrt(x+y)
          fprintf("z = %g\n", z)

??

evalc('x=2; y=3; z=sqrt(x+y); fprintf("z = %g\n", z);')

changes ans to z = 2.23607(newline) and it is not clear you would want that as your Data property.

When you permit the user to input the commands and you execute them with evalc(), the only output you can expect is a character vector. You can split the character vector by lines, such as

regexp(evalc('x=2; y=3; z=sqrt(x+y); fprintf("z = %g\n", z);'), '\n', 'split')