sending an error message to the user

Question

Sarah Chappell-Smith 2016-11-28

0
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https://ww2.mathworks.cn/matlabcentral/answers/314328-sending-an-error-message-to-the-user

回答： Image Analyst 2016-12-4

I am trying to write a code where the user is asked to input a value however the value must be (0<x<=0.25)how can I send the user a error message if they do not enter a value within the limits and allow them to attempt another input?

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Answer 1

KSSV 2016-11-28

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https://ww2.mathworks.cn/matlabcentral/answers/314328-sending-an-error-message-to-the-user#answer_244988

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function Hello(x)
if  ~(x >0 && x <= 0.25)
    error('input is not 0<x<=0.25')
end

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KSSV 2016-11-29

How you want to use the function? In the above no where you have called the function.

Sarah Chappell-Smith 2016-12-4

在 MATLAB Online 中打开

I've managed to get it to work using;

while f0 <= 0 f0>0.25

f0=input('Enter a value for the Fourier Number: ');

end

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Answer 2

Image Analyst 2016-12-4

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https://ww2.mathworks.cn/matlabcentral/answers/314328-sending-an-error-message-to-the-user#answer_245916

在 MATLAB Online 中打开

Use errordlg() or helpdlg() wrapped inside a uiwait():

Try this snippet:

% Ask user for two floating point numbers.
defaultValue = {'45.67', '78.91'};
titleBar = 'Enter a value';
userPrompt = {'Enter floating point number 1 : ', 'Enter floating point number 2: '};
caUserInput = inputdlg(userPrompt, titleBar, 1, defaultValue);
if isempty(caUserInput),return,end; % Bail out if they clicked Cancel.
% Convert to floating point from string.
usersValue1 = str2double(caUserInput{1})
usersValue2 = str2double(caUserInput{2})
% Check for a valid number.
if isnan(usersValue1)
    % They didn't enter a number.  
    % They clicked Cancel, or entered a character, symbols, or something else not allowed.
  % Convert the default from a string and stick that into usersValue1.
    usersValue1 = str2double(defaultValue{1});
    message = sprintf('I said it had to be a number.\nTry replacing the user.\nI will use %.2f and continue.', usersValue1);
    uiwait(warndlg(message));
end
% Do the same for usersValue2