Explain how many times a for loop will execute

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Jorge Rodriguez 2020-10-10

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https://ww2.mathworks.cn/matlabcentral/answers/610021-explain-how-many-times-a-for-loop-will-execute

评论： Jorge Rodriguez 2020-10-10

I can add ires to see the result, I am not sure how to see how many times the loops will execute. If someone could explain how to do this that would be helpful. I have done several searches and tried using the break function, but if its really big number says -32687:32688, how does one tell how many times it loops. without counting each 64560 times. I have figured it out on smaller loops by putting the ii at the bottom of the code. This has a loop within a loop and I am lost.

ires = 0;
    for index1 = 10: -2: 1
        for index2 = 2:2:index1
           if index2 == 6
           break;
           end
      ires = ires + index2;
        end
    end

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回答（1 个）

Mario Malic 2020-10-10

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https://ww2.mathworks.cn/matlabcentral/answers/610021-explain-how-many-times-a-for-loop-will-execute#answer_510301

在 MATLAB Online 中打开

ires = 0;
for index1 = 10: -2: 1
    for index2 = 2:2:index1
       if index2 == 6
       break;
       end
       ires = ires + 1; % index2 for what?
    end
end

MATLAB enters first loop with index1 = 10, then proceeds in the second loop with index2 = 2. Within second loop it checks the if condition and adds 1 to ires. When the 'if' condition is fulfilled, it exits the second loop, and returns in the first one with index1 = 8 and so on.