Leave the whole for-loop

Question

Anna 2013-8-30

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https://ww2.mathworks.cn/matlabcentral/answers/85996-leave-the-whole-for-loop

How can I leave the loop completely, if an "if" statement in that loop turns out to be true? I have tried break, but I guess that doesn't work in if-structures... My code structure looks like this:

 for i = 1:5
      (doing some stuff here)
     if [something happens]
         for [...], for [...], (assignments); end, end, 
                    !and STOP COMPLETELY no further calculations are needed!
     else
         for [...], (assignments ); end
     end 
   (doing more stuff)
end

Thanks for any help!

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Answer 1

Geert 2013-8-30

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编辑：Geert 2013-8-30

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Why can't you use break? The break command can perfectly be used in combination with if statements. Break will execute the innermost for (or while) loop it is in...

Consider the following example:

   for ii = 1:10
       disp(['Current value of ii = ', num2str(ii)])
       if ii>5
           % execute some for loops
           for kk=1:5
               for ll=1:5
                   % put your commands here
               end
           end
           % exit the for loop
           break 
       else
           for kk=1:5
              % do something here 
           end
       end 
   end
   disp(['for loop was stopped at the moment that ii = ', num2str(ii)])

The break command will exit the innermost loop (type: help break):

break Terminate execution of WHILE or FOR loop.
    break terminates the execution of FOR and WHILE loops.
    In nested loops, break exits from the innermost loop only.

Does this clarifies it for you?

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Simon 2013-8-30

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If you want to exit both loops from inside the innermost loop, try setting a bool variable before the loops

exitloop = false

Now you can set this variable to true in the inner loop and catch this in the outer loop like

if exitloop
  break
end

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Answer 2

David Sanchez 2013-8-30

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The break command exists the most inner for/while loop. For nested for loops, you have to set a flag so that when it is active, the whole loop finishes. Following you code structure, break should exit:

 for i = 1:5
      (doing some stuff here)
     if [something happens]
         for [...], for [...], (assignments); end, end, 
                    !and STOP COMPLETELY no further calculations are needed!
         break  % this break here will cause to get out of the main for-loop since it is not place within another for-loop
     else
         for [...], (assignments ); end
     end 
   (doing more stuff)
end

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Answer 3

Anna 2013-8-30

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https://ww2.mathworks.cn/matlabcentral/answers/85996-leave-the-whole-for-loop#answer_95521

Thank you all for the excellent answers! You are totally right Geert, break works perfectly fine. I just had a different error in my code, and I had read something that threw me off when I googled my question, that's why I thought break doesn't work in if-structures. Everything works exactly as needed. Thanks again!