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

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Jucimar Carpe
Jucimar Carpe 2019-8-18
评论： Jucimar Carpe 2019-8-18
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

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采纳的回答

Adam Danz
Adam Danz 2019-8-18
编辑：Adam Danz 2019-8-18
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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Adam Danz
Adam Danz 2019-8-18
Do you mean a certain input is not producing the expected output with the code from my answer? Or is there a different problem?
Jucimar Carpe
Jucimar Carpe 2019-8-18
I let in this way.
It seems the instruction ~isnan let the variable Sbase_gerador with some random number (that i dont know what it is) because of the logical answer. And this make my calculations crazy.
Sbase_gerador = ~isnan(str2double(strrep((app.potencia.Value),',','.')))
if ~Sbase_gerador
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

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