msgbox and then do nothing.

Question

Nam Pham 2015-11-5

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https://ww2.mathworks.cn/matlabcentral/answers/253166-msgbox-and-then-do-nothing

编辑： Nam Pham 2015-11-6

Hello I am writing a GUI program, input (+)and (0), if I input (-), I want it show error box, do nothing. In my code, If I input (-) it show error box but it still run plot. How do I have to do? Thank you!

   function pushbutton1_Callback(hObject, eventdata, handles)
  temp = get(handles.signal,'string');
  temp=strrep(temp,'+',2);
  temp=strrep(temp,'0',0);
  temp=strrep(temp,'-',1);
  for i=1:length(temp)
      if temp(i)==1
          msgbox(' Only + and 0');
          break;
      end
  end
  n=200;
  t=0:1/n:length(temp);
  x=zeros(1,length(t));
  for i=0:length(temp)-1
      if temp(i+1)==2
          x(i*n+1:(i+1)*n)=1;
      elseif temp(i+1)==0
          x(i*n+1:(i+1)*n)=0;
      end
  end  
plot(t,x,'LineWidth',3);
axis([0 t(end) -0.1 1.1]);
grid on;
title([' Bitstream: [' num2str(bitstream1) ']']);

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Answer 1

Guillaume 2015-11-5

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https://ww2.mathworks.cn/matlabcentral/answers/253166-msgbox-and-then-do-nothing#answer_198584

编辑：Guillaume 2015-11-5

在 MATLAB Online 中打开

Replace break by return.

Note that you do not need the for loop, use any and vectorised comparison instead

%...
temp=strrep(temp,'-',1);
if any(temp == 1)
   msgbox(' Only + and 0');
   return
end

Your code is very fragile. What if the user enters '*'? You don't detect that.

In your previous question (which you seem to have abandoned) I showed a much more efficient and robust way of converting your input string.

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Guillaume 2015-11-6

在 MATLAB Online 中打开

The proper syntax would be

if any(temp ~= 2 % temp ~= 0)

Note the & instead of && because it's a vector operation.

As per my answer to you previous question, a cleaner way of achieving your test is with:

usermessage = get(handles.signal,'string'); %temp is a terrible variable name
if ~all(ismember(strsplit(usermessage), {'+', '0'}))
    msgbox('Only + and 0 are allowed');
    return;
end

The best way to get help is to post question in this forums as you've done so far. That way you get feedback from multiple people. My contact details are not public on purpose.

Nam Pham 2015-11-6

编辑：Nam Pham 2015-11-6

在 MATLAB Online 中打开

Firstly, sorry for my bad English, and thank you very much. I am new to learn MATLAB. I have to creat a GUI that user input signal and output bitstream. Line coding as NRZ,HDB3, B8ZS.... why

if any(temp ~= 2 % temp ~= 0)

but not

if any(temp~=2 && temp ~=0)

And strsplit command doesn't work. can you write full code and test, I tried much time but it doesn't work

usermessage    = '+ + 0 - - + + - - + -';
if ~all(ismember(strsplit(usermessage), {'+', '0'}))
  msgbox('Only + and 0 are allowed');
  return;
end

And here is my full code for Unipolar NRZ

 function pushbutton1_Callback(hObject, eventdata, handles)
usermessage = get(handles.signal,'string');
usermessage=str2num(strrep(strrep(strrep(usermessage,'+','2'),'-','1'),'0','0'));
bitstream=zeros(1,length(usermessage));
n=200;
t=0:1/n:length(usermessage);
x=zeros(1,length(t));
%kiem tra loi
for i=1:length(usermessage)
    if usermessage(i)~=2&&usermessage(i)~=0
        msgbox('Only + and 0 are allowed');
        return;
    end
end    
% ve song
for i=0:length(usermessage)-1
    if usermessage(i+1)==2
        x(i*n+1:(i+1)*n)=1;
    elseif usermessage(i+1)==0
        x(i*n+1:(i+1)*n)=0;
    end
end
% xuat bit
for i=1:length(usermessage)
    if usermessage(i)==2
        bitstream(i)=1;
    elseif usermessage(i)==0
        bitstream(i)=0;
    end
end
set(handles.bitstream,'String',num2str(bitstream));
plot(t,x,'LineWidth',3);
axis([0 t(end) -0.1 1.1]);
grid on;
title([' Bitstream: [' num2str(bitstream) ']']);

How do you feel my code? What I should edit?

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msgbox and then do nothing.

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