Problem with break statement

I have a code:

for i=1:n
   for j=1:n
       if 'some condition'
          'some logic'
         if 'some condition'
           break
        end 
      end
    end
end

now my question is that if the 2nd if statement is true and it breaks shouldnt it end the 2nd for loop since if statement is under 2nd for loop but whenever I run this if the 2nd if statement is true and it breaks it ends the 1st for loop.

Any guidance is highly appreciated.

Answer 1

[Adam Danz]

> ...shouldn't it end the 2nd for loop since if statement is under 2nd for loop... ?

Yes, it should end the 2nd loop and that's what it's doing. To better understand what's going on, I inserted fprintf commands in each loop so you can see the iteration numbers. The first condition is true when j==2 and the second nested condition is true when i==3 (while j is equal to 2).

clc
n = 4;
for i=1:n
    j = NaN;
    fprintf('\n i=%d, j=%d',i,j)
    for j=1:n
        fprintf('\n i=%d, j=%d',i,j)
        
        if j==2
            fprintf(' CONDITION 1')
            
            if i==3
                fprintf(' & CONDITION 2: breaking')
                break
            end  % end i==2 test
            
        end % end j==2 test
        
    end
end
fprintf('\n')

You can see (below) that the break condition occurs when i==3 and j==2 and on the next iteration, the i-loop interates to i==4 and the j-loop resets.

[Anurag Gupta]

Hey Adam,

Thanks for answering my question and clearing my doubt.

[Anurag Gupta]

As can be seen in the command window that when the break occurs j goes to NaN again and our code starts to run from i=whatever_is_next. what I want to do is whenever this break occurs I want to continue with j=whatever_is_next. can you give a solution for this. if there is a way please consider answering.

[Adam Danz]

If I understand you correctly, you just need to remove the break.

By the way, j doesn't really turn to NaN, I just depicted it that way to show that the i-loop has reset and therefore the j-loop will too.

[Adam Danz]

Or do you want to iterate to the next i but then start on what would have been the next j in the previous i-iteration?

If so, try this,

jHolder = -inf;
for i=1:n
    j = NaN;
    for j=1:n
        if condition1
            % Do something
            if condition2 && j>jHolder
                % Do something
                jHolder = j; 
                break
            end 
        end 
    end
end
fprintf('\n')

[Anurag Gupta]

Hey Adam,

after that break statement I have a huge line of codes so what I want to do is skip those line of codes and continue with the same i and next possible j. like for example if i=1 and j=2 and when it enters the if loop and the consition is true it should break and not execute all the lines below break and continue again with i=1 and j=3. is there a solution for this.

I am a beginner in MATLAB now so this help will be highly appreciated.

Thanks in advance.

[Adam Danz]

Ahhhhhh...... what you're looking for in the continue function.

If that was described better from the start, this answer would have been just a few words! 😀

So, replace break with continue.