Why i am getting this error message

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Robiul Ferdous
Robiul Ferdous 2018-7-25
评论： OCDER 2018-7-26
function pushbutton1_Callback(hObject, eventdata, handles)
% hObject handle to pushbutton1 (see GCBO)
% eventdata reserved - to be defined in a future version of MATLAB
% handles structure with handles and user data (see GUIDATA)
clc
s =str2double(get(handles.edit1,'string'));
in =str2double(get(handles.edit2,'string'));
en =str2double(get(handles.edit3,'string'));
t=s:in:en;
y=eval(get(handles.edit4,'string')); %line 181
figure(1)
plot(t,y)
title('Actual graph')
x=0;
y1 = zeros(1,(length(t)-1));
for i=1:(length(t)-1)
x=x+(y(1,i+1)*in);
y1(1,i)=x;
end
t1=s:in:(en-in);
figure(2)
plot(t1,y1)
title('After Intregation')
  1 个评论
Christopher Wallace
Christopher Wallace 2018-7-25
What is on line 181?
Please reformat the code in the question. It isn't possible to see where the lines end.

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采纳的回答

OCDER
OCDER 2018-7-25
The error you're getting is probably caused by an invalid/empty string in handles.edit4. And DON'T use eval, esepecially in a GUI's editable text!
y = eval('')
Error: This statement is incomplete.
y = eval(get(handles.edit4,'string')); %DON'T USE EVAL! Security Risk!
% What if handles.edit4.string = 'delete(every_file)' ? You'll lose a lot of files!
What are you "evaluating"? Give us an example and we'll provide a safer and faster alternative to eval.
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OCDER
OCDER 2018-7-25
I see. This clears up the blacklist vs whitelist approach. The other issue was what if the whitelist wasn't so obvious or is large? EX:
tanh(t) + sech(t) + ... more trig func
One way to get a larger whitelist would be:
SafeStr = arrayfun(@(x) strrep(x.name, '.m', ''), dir(fullfile(ctfroot, 'toolbox', 'matlab', 'elfun', '*.m')), 'un', 0)
Now more functions for trig are valid.
Walter Roberson
Walter Roberson 2018-7-25
Interesting approach.
Though this does accidentally bring in the script 'Contents' (which is effectively just a help file script.)

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更多回答（1 个）

Robiul Ferdous
Robiul Ferdous 2018-7-26
how can i solve the error in matlab graphics internal fig file while evaluating ui control callback.
  1 个评论
OCDER
OCDER 2018-7-26
The Answer is reserved for answer to your original question. If this is a new error and new question, post a new question. Otherwise, no one will try to respond here as an Answer was already accepted.
Post full error message in you new question post. Read this:
https://www.mathworks.com/matlabcentral/answers/6200-tutorial-how-to-ask-a-question-on-answers-and-get-a-fast-answer

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