How do I break while loop

Hi guys, I'm new to matlab. I have to following code. I want to break the while loop if enter valid promocode(HAPPY10) and when ask_promocode=='N'. How can I do? sending SOS to all the expert here;'(

Thank you in advace for helping me

ask_promocode=input('Do you have any promocode?Y or N ','s');
if ask_promocode=='Y'
    
while str_promocode=='HAPPY10'
    str_promocode=input('Please enter your promocode=','s');
	
    if str_promocode=='HAPPY10'
        fprintf('Congrats!You can have the discount capped at RM5\n');
        break
    end
    else
        fprintf('Oh dear, you have enter invalid promocode!\n')
    end

	elseif ask_promocode=='N'
	    fprintf('Ohh It is sad to heard that! Dear you may proceed to payment now<3 \n');
	    break
	end
	 
	 else 
	fprintf('Hi dear, we can not reach you. Try again!\n');
	end
end
	

[David Fletcher]

A few observations that may (or may not) help:

The program will never (or should never) enter the while loop since the input for the promocode is after the decision to enter the loop. In reality it may enter because the == operator probably will give you something you didn't quite expect. You would be better using the strcmp function for the condition on the while loop - try typing 'HAPPY10'=='HAPPY12' - is the result what you expected). Though, as mentioned above the promocode input needs to be before the loop enters or the loop condition will never be satisfied.

The if str_promocode=='HAPPY10' decsion in the while loop is redundant - to get to that point str_promocode must be 'HAPPY10' since it is the condition on the loop. Though again, look at using strcmp instead of the == operator

[poor kitty]

Hi, thank you for your quick response. Do you mean by this? Sorry, I just expose to this strcmp function

str_promocode = input('Please enter your promocode=','s'); 
 % save the result, of the ask_promo being compared to the character 'Y', 
 % in the variable "str_promocode" 
         
  HAPPY10= strcmp(str_promocode, 'Y'); 
 
% Now do something based on this information. 
if ( HAPPY10 ) 
    fprintf('Congrats!You can have the discount capped at RM5\n');
else
     fprintf('Oh dear, you have enter invalid promocode!\n')
     end 

[David Fletcher]

That is how the function is applied - in this instance HAPPY10 would contain a true/false result based on a comparison between whatever the user entered in str_promocode and the character 'Y' (though you might want to compare it against the actual promocode of 'HAPPY10' rather than 'Y' since you';ve asked the user to enter a promocode, rather than whether or not they have a promocode)

You may want something more like this - I've left out the 'cannot reach you' bit since I wasn't sure what it meant (possibly if the user enters something other than 'Y' or 'N' to the having a promocode question?).

clear
ask_promocode=input('Do you have any promocode?Y or N ','s');
    
while strcmp(ask_promocode,'Y')
    
    str_promocode=input('Please enter your promocode=','s');
	
    if strcmp(str_promocode,'HAPPY10')
        fprintf('Congrats!You can have the discount capped at RM5\n');
        break
    else
        fprintf('Oh dear, you have enter invalid promocode!\n')
    end
end
    
if strcmp(ask_promocode,'N')
	    fprintf('Ohh It is sad to heard that! Dear you may proceed to payment now<3 \n');
end

[poor kitty]

Thank you so much. It helps a lot! But I did some changes for

if strcmp(ask_promocode,'N')

to

while strcmp(ask_promocode,'N')
fprintf('Ohh It is sad to heard that! Dear you may proceed to payment now<3 \n');
break
end

Once again thank you for your help.It means a lot to me. luv you 3000 <3

[David Fletcher]

Ok - you are using loops like if constucts rather than the normal function of a loop, but whatever works for you.

Answer 1

[Sulaymon Eshkabilov]

This has to be removed:

if ask_promocode=='Y'  

end

Because "while ... end" loop will take care of this issue that makes a user enter "Y" or "N". This is not very robust though as is, but it works.

The crucial error in your code is that while loop never gets its set condition met, e.g.:

while str_promocode=='HAPPY10'

That can be substituted with:

while isempty(str_promocode)  % if a user skips to enter any any answer, then it has to keep asking to input Y or N
   str_promocode=input('Please enter your promocode=','s');
   ...
end
%% 

[poor kitty]

Hi, thank you for your response. But when I remove

if ask_promocode=='Y'

it doesn't work :'(

    while isempty(str_promocode)
        str_promocode=input('Please enter your promocode=','s');
        if str_promocode=='HAPPY10'
            fprintf('Congrats!You can have the discount capped at RM5\n');
        else
            fprintf('Oh dear, you have enter invalid promocode!\n');
        end
   
elseif ask_promocode=='N'
	 fprintf('Ohh It is sad to heard that! Dear you may proceed to payment now<3 \n');
	    
    else 
	fprintf('Hi dear, we can not reach you. Try again!\n');
        end
end

Sorry, I can't catch the ball. Can you please explai more about it?