Testing if an input is numeric or character

Hi folks, i'm implementing a software on appDesigner and i want to prevent wrong entries from users.

I've tried to use the folowing code but it's not working. My gol would be, check if the user entered with a number or character. If it's a number then OK, otherwise open a warning dialog box informing the error and then stop the program.

I don't know how to get the logical answer of "teste_potencia" and use it!

The way i've writed it's not working.

           Sbase_gerador = str2double(strrep((app.potencia.Value),',','.')); 
           
           teste_potencia = isnumeric(Sbase_gerador)
            
            if ~teste_potencia
                opts= struct('WindowStyle','modal','Interpreter','tex');
                potencia_incorreta = warndlg('\fontsize{11}Caracteres diferentes de números não são aceitos.',...
                    'Entrada incorreta de dados', opts);
                app.potencia.Value='0';

            end

Answer 1

[Stephen23]

if isnan(Sbase_gerador)
    ...
end

[Jucimar Carpe]

Hi Stephen, thank you very much for you help!!!

The code now has changed and now i got the right solution as you can see below.

I only have one more question, when the user entry with a character it opens the warning dialog box, but it doesn't stop the calculation and show some graphs.

Is it possible to stop the program?

            Sbase_gerador = str2double(strrep((app.potencia.Value),',','.')); 
            teste_Sbase_gerador = isnan(Sbase_gerador); 
            if teste_Sbase_gerador==true
                opts= struct('WindowStyle','modal','Interpreter','tex');
                potencia_incorreta = warndlg('\fontsize{11}Caracteres diferentes de números não são aceitos.',...
                    'Entrada incorreta de dados', opts);
                app.potencia.Value='0';
            end

[Stephen23]

"Is it possible to stop the program?"

Depending on how you want to "stop" the program, one of these might work for you:

• return
• break
• error
• keyboard
• if followed by some other code...

"thank you very much for you help!!!"

My pleasure! If it helped you don't forget to accept my answer!

[Jucimar Carpe]

Thank you again!