is it allowed to update the cycle variable?
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回答（1 个）
Walter Roberson
2015-10-17
You can change the index variable within a "for" loop, and the change in value will last to the end of the iteration. As soon as the next iteration starts the new value assigned will ignore any change you made. For example,
for K = 1 : 5
disp(K); %first time through would be 1, second time through would be 2
K = K * 10; %allowed
disp(K); %first time through would be 10, second time through would be 20
end
Notice that the second time through the loop the change of K from 1 to 10 in the first iteration has no effect on what happens for the second iteration.
4 个评论
per isakson
2015-10-17
Yes, but ...
Walter Roberson
2015-10-17
The question was "is it allowed" and the answer is "Yes". And now I have clarified the effect it has.
per isakson
2015-10-18
编辑：per isakson
2015-10-18
Yes, your answer is correct. I don't question that.
However, the documentation says: "Avoid assigning a value to the index variable within the loop statements." And I cannot think of a good reason to do it.
Walter Roberson
2015-10-18
I cannot think of a good reason to do it either.
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2015-10-18
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