My code works as a script file but produces errors as a GUI function, how do I fix it?

I managed to get the code in the last thread I posted working, however, since it is a GUI project, I need to transfer it from the script file I worked it on, onto the main GUI file. Here is the code for the function file:

function rowcolPush_Callback(hObject, eventdata, handles)
str = get(handles.plainText, 'String');
key = get(handles.keyText, 'String');

numKey = double(upper(str2num(key)));
sortKey = sort(numKey);
numArray = double(upper(str));
spaceArray = numArray(~isspace(numArray));
lenStr = numel(spaceArray);
lenKey = length(key);
array = zeros(round(lenStr/lenKey),lenKey);

if rem(lenStr,lenKey) ~= 1
    spaceArray(1,(numel(array)-lenStr)+lenStr) = double('X');
end

outputArray = reshape(spaceArray,lenKey,round(lenStr/lenKey))';

%------

x = find(numKey ~= sortKey);
x2 = x([2,1]);

if isempty(x) == 0
    outputArray(:,x) = outputArray(:,x2);
end

outputNum = reshape(outputArray(:,1:end), [1 20]);
outputStr = char(outputNum);

set(handles.cipherText,'String',outputStr);
guidata(hObject, handles);

I start getting errors at the %---- mark. x2 returns an error while indexing, saying that the index exceeds matrix dimensions. If I try to comment that part out and skip to outputNum, it gives an error with reshape, saying that the number of elements must not change in order to reshape.

When I run this code (defining str as 'TO SERVE AND TO PROTECT' and key as 'ALERT') as a script file without any functions, it works fine and produces the output I want. However, running this code in the GUI doesn't work. Is there something I'm forgetting/missing?

For reference, I am using the same string and key in the GUI and script file.

Answer 1

[per isakson]

One observation

sortKey = sort(numKey);
...
x = find(numKey ~= sortKey);
x2 = x([2,1]);

x will be empty if numkey is already sorted.

Set a breakpoint an check the size of x.

And

numKey = double(upper(str2num(key)))

str2num is not intended for letters; it returns empty for letters

See

https://se.mathworks.com/help/matlab/matlab_prog/debugging-process-and-features.html

https://se.mathworks.com/help/matlab/matlab_prog/examine-values.html

[Samir Saidi]

It turns out my error was with str2num, removing it made x and x2 work, while I had made another mistake in changing numArray and spaceArray (spaceArray was defined first in the script file, and numArray was defined next) so I returned those to the same values the script file had and now my program works. I also didn't know about the debugging feature; that's how I caught the mismatch in array values. Thanks!