MATLAB: Testing if a input is a numerical (double) of character

appdesignerMATLAB

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.
The way i've writed it's not working.
 Sbase_gerador = str2double(strrep((app.potencia.Value),',','.'));% Read entry data and convert comma to '.' if needed
            
            teste_potencia = isnumeric(Sbase_gerador)
            if teste_potencia==0
                opts= struct('WindowStyle','modal','Interpreter','tex');
                tensao_incorreta_t2 = warndlg('\fontsize{11}Caracteres diferentes de números não são aceitos.',...
                    'Entrada incorreta de dados', opts);
                app.potencia.Value='0';
            end

Best Answer

You can use str2double() to convert the string to numeric. If the string did not contain something that can be converted to numeric, it will return NaN. 
isNumber = ~isnan(str2double(str));
Examples
isNumber = ~isnan(str2double('100'))            % true



isNumber = ~isnan(str2double(' 100 '))          % true
isNumber = ~isnan(str2double('3.1415926'))      % true
isNumber = ~isnan(str2double('8.3205e+24'))     % true
isNumber = ~isnan(str2double('Abcd'))           % false

isNumber = ~isnan(str2double('5 and 7'))        % false
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