Use of break in if?

Question

Adnan Ali 2014-8-20

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/151643-use-of-break-in-if

回答： Jan 2021-4-15

Here is my code i Want to use break/continue after First if Ends. as i have mention it there. but we cant use break in IF. I need alternative of it. Note: there are two times if(Stroke_counter==1) in code. that is not because of mistake

    if(Stroke_counter==1)        
        if (((S==1)||(E==1)) &&( (y==2)) )                    
                    msgbox('This is One','Recognize');
                    end                                            
        elseif( (x==1)&&(y==1)&&(x==1) &&(y==1) &&(S==2))                           
                    msgbox('This is two','Recognize');
                    end                    
        elseif((x==1)&&(y==1)&&(x~=1))
                    msgbox('This is three','Recognize');
                    end
         beak;
        else
                    msgbox('Not Found...','error');  
        end
    else
        msgbox('Not in 1 step','error');  
    end
    if(Stroke_counter==1)        
        if (((S==1)||(D==1)) &&( (y==2)) )                    
                    msgbox('This is four','Recognize');
                    end                                            
        elseif( (x==1)&&(y==1)&&(D==1) &&(y==1) &&(S==2))                           
                    msgbox('This is five','Recognize');
                    end                    
        elseif((x==1)&&(F==1)&&(x~=1))
                    msgbox('This is Six','Recognize');
                    end
        else
                    msgbox('Not Found...','error');  
        end
    else
        msgbox('Not in 2 step','error');

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David Sanchez 2014-8-20

What is the point on using a break within an if statement?

If the condition is fulfilled, the following else will not count in your code anyway.

Lorenzo TORRICELLI 2021-4-15

For example, if a block of instructions is common to a number of conditions, whereas a certain case is exceptional.

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Answer 1

Adam 2014-8-20

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/151643-use-of-break-in-if#answer_149225

If you want to break after the first If ends then you won't be in the If to place your break/continue. And if you were able to place one there then why not just delete the second if since it would never execute.

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Adam 2014-8-20

在 MATLAB Online 中打开

Just use a boolean then as

answerFound = false;

then update it in each if statement and then AND it together with the following if statements as e.g.

if( ~answerFound && Stroke_counter==1)

To be honest though this sounds like such a large block of code it should be a function by itself (probably many, but that's a side issue) so you can just put

return

to return early from the current function and then carry on your algorithm in the function that calls this one.

Adnan Ali 2014-8-21

return is working. but truly speaking I found matlab behavior too much annoying in this case. Thanks for your Help.

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Answer 2

Jan 2021-4-15

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/151643-use-of-break-in-if#answer_675851

在 MATLAB Online 中打开

"MAtlab donot work in more than 6 (if() elseif() else end)" - of course Matlab handles much more nested IF branchs than 6.

Checking a lot of different conditions with a pile of IF commands creates code, which is hard to read and to debug. It is too prone to typos like in your code:

((x==1) && (y==1) && (x~=1))

This cannot be TRUE, because x==1 && x~=1 cannot happen. So it is not Matlab, but the programming style, which causes problems here.

This is not useful also:

elseif( (x==1) && (y==1) && (x==1) && (y==1) &&(S==2)) 
%                           ^^^^^^^^^^^^^^^^ tested twice ?!

Your code is not valid at all due to the orphand end commands:

        if (((S==1)||(E==1)) &&( (y==2)) )                    
                    msgbox('This is One','Recognize');
                    end  % <== Nope, no END before ELSEIF
        elseif