while lopps. help plz ´,

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Jian Gui 2014-6-23

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评论： Jian Gui 2014-6-24

Hi all. I am trying to make a while loops that will keep on running if the user input is a str, a number less and equal 0 or the number is longer the length of my vector. But it doesn't work, plz help:)

deleterowStr=input('Please enter the number of the row:','s');
deleterow=str2num(deleterowStr);
while ~((~isempty( deleterow) &&  deleterow <=0 || deleterow > length(W)) || strcmpi(deleterowStr,'')==1)
    disp('Invaild row number')
    deleterowstr=input('Please enter the number of the row:','s');
    deleterow=str2num(deleterowstr);
end

thx:)

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Joseph Cheng 2014-6-23

duplicate post http://www.mathworks.com/matlabcentral/answers/137126-problem-in-while-loop-when-input-is-characters-or-words

anyways. I would suggest put a break point in and see why you do not meet the criteria to breakout of the loop.

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Answer 1

Joseph Cheng 2014-6-23

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在 MATLAB Online 中打开

okay so doing a quick testing with different inputs the issue is when you put in an input like 'a'. where the logic checks would become empty. So what i did is broke it out and when the deleterow number is empty put one of the other conditionals so it would loop again. It would break out of the loop iff none of the loop conditions are met.

    W=[1 2 3 4 5]
    deleterowStr=input('Please enter the number of the row:','s');
    deleterow=str2num(deleterowStr);
    while 1
        inputEmpty = isempty(deleterow);
        if inputEmpty==1
            deleterow = -1;
        end
        inputNeg = deleterow<=0;
        input2Long = deleterow>length(W);
        inputBlank = strcmpi(deleterowStr,'')==1;
        if sum([inputEmpty inputNeg input2Long inputBlank])==0
            break
        end
        disp('Invaild row number')
        deleterowstr=input('Please enter the number of the row:','s');
        deleterow=str2num(deleterowstr);    
    end
        W(deleterow) = []

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Joseph Cheng 2014-6-23

在 MATLAB Online 中打开

condensed version

W=[1 2 3 4 5]
deleterowStr=input('Please enter the number of the row:','s');
deleterow=str2num(deleterowStr);
if isempty(deleterow)
    deleterow = -1;
end
while (deleterow<=0 || deleterow > length(W)) || strcmpi(deleterowStr,'')==1
    disp('Invaild row number')
    deleterowstr=input('Please enter the number of the row:','s');
    deleterow=str2num(deleterowstr);   
    if isempty(deleterow)
        deleterow = -1;
    end
end
    W(deleterow) = []