While loop question, one too many loops happens.

Question

Dan Po 2016-10-11

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/306744-while-loop-question-one-too-many-loops-happens

回答： Dan Po 2016-10-15

I want the counter to stop counting once the value '1' is entered. If '1' is entered when running this script, the while loop runs once more before ending. I do not want this. Am I using break the wrong way, or is something else happening?

Thanks

 counter=0;
    y_n=0;
    while y_n==0
        if y_n==1
            break
        end
       counter=counter+1
    y_n= input('enter 1 or 0\n')
    end

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Answer 1

Walter Roberson 2016-10-11

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https://ww2.mathworks.cn/matlabcentral/answers/306744-while-loop-question-one-too-many-loops-happens#answer_238476

You just tested that y_n == 0 in the while statement. It cannot have changed value by the very next statement, at which point you test whether y_n==1 . You should move the "if" to after the input() .

Question: What do you want to have happen if the user enters (for example) 2.134473 ? That is not 0 so the while condition will no longer be true, but the if y_n==1 would be false.

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Dan Po 2016-10-11

Input is not mobile supported. Goodnight.

Dan Po 2016-10-11

编辑：Dan Po 2016-10-11

在 MATLAB Online 中打开

The matlab online app works as I want, but I will check if my desktop version runs correctly. I was using a live script and was not getting my wanted output. Thank you for your help.

format compact
clear
clc
counter=0;
  y_n=0;
  while y_n==0
         y_n= input('enter 1 or 0 to continue or end the loop \n');
      if y_n==1
          break
      end
     counter=counter+1;
fprintf('this is loop %d\n',counter)
  end
  fprintf('the final count of loops is %d\n',counter)