Changing the step in a for loop

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Alexandru Miculescu
Alexandru Miculescu on 8 Mar 2015
Commented: Guillaume on 8 Mar 2015
Hi! Easy question for you guys! How can i get the same output in matlab? Here's the code in c++ where the output is 0, 2, 4, 6, 8, whereas in matlab is 1 to 10. Thanks!
if true
for (int i = 0; i < 10; i++)
{
cout << i << " ";
i = i + 1;
}
for i=0:9
i = i+1
end
}

Answers (3)

Stephen23
Stephen23 on 8 Mar 2015
Edited: Stephen23 on 8 Mar 2015
for k = 0:2:8
... some code here
end
Or even better would be to forget about those low-level loops like you need in C, and learn to vectorize your code. The documentation states:
Vectorizing your code is worthwhile for several reasons:
  • Appearance: Vectorized mathematical code appears more like the mathematical expressions found in textbooks, making the code easier to understand.
  • Less Error Prone: Without loops, vectorized code is often shorter. Fewer lines of code mean fewer opportunities to introduce programming errors.
  • Performance: Vectorized code often runs much faster than the corresponding code containing loops.
Forget about low-level languages, and learn to utilize MATLAB's programming concepts.

Alexandru Miculescu
Alexandru Miculescu on 8 Mar 2015
Edited: Alexandru Miculescu on 8 Mar 2015
Thank you for your answer, i'll check that link.
for i=1:nr_games
if ( 1+fix(6*rand) ) == 6
i=i+1; % here i want to increment the i
if ( 1+fix(6*rand) ) == 6
luck = luck + 1;
end
end
What i realy want to do is to increment manually the step when ( 1+fix(6*rand) ) == 6, because i generated myself another random number.

Jos (10584)
Jos (10584) on 8 Mar 2015
For-loops in matlab behave a little different than for loops in C. You might be in need of a While-loop.
for k=1:5
disp(k)
k = 100 ;
end
for k = [10 3 5 6]
disp(k) ;
end
k = 1 ;
while k < 5
k = k + 2 ;
disp(k)
end
  1 Comment
Guillaume
Guillaume on 8 Mar 2015
To follow up on Jos' answer, you need to understand that for just iterates over the columns of the vector/matrix that you give it. In C++ terms, it behaves like std::for_each on a const sequence.

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