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No output from a for and elseif loop

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Hi,
I am trying to get the J matrix from the following simple code, however I receive no output for J:
str=readline('1C1S.txt','all');
P=strfind(str,'w');
for x=1:numel(str)
if isempty(P(x,1))
J=1;
elseif isequal(P(x,1),[9])
J=2;
elseif isequal(P(x,1),[4])
J=3;
elseif isequal(P(x,1),[4 9])
J=4;
end
end
  2 Comments
Mohammad R. Ghassemi
Mohammad R. Ghassemi on 15 Oct 2021
It is a useful function I have downloaded from the MathWorks.
It reads all strings from a text file (line by line) as they are (including spaces etc.).

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Accepted Answer

DGM
DGM on 15 Oct 2021
Edited: DGM on 15 Oct 2021
That should be readlines().
P is a cell array of numeric vectors, so address it accordingly.
Any assignment to J overwrites the prior value in J.
The case where none of the conditional tests is true is not handled.
The equality tests are probably wrong, but since there's no description of the intended logic, I don't know what to tell you.
To summarize:
isequal(P(x,1),[4 9])
is never true, because P(x,1) is a cell scalar, which is never equal to any numeric vector.
isequal(P{x,1},[4 9])
is only true if the vector in P{x,1} is identical to [4 9]. That is, it needs to be the same length and all elements must match.
  2 Comments
Mohammad R. Ghassemi
Mohammad R. Ghassemi on 15 Oct 2021
Thanks a lot. I indexed J as J(x,1) and now I have the required complete output.

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