Getting out of while loop when user says end

I have an image I am taking basic two point measurements on. The user is asked if they want to make another measurement and has the option of 'Yes', 'No', 'Cancel'. They can take as many or as few measurements as they want. I want to start this up if the answer is 'Yes' and re-ask the question after every measurement and keep looping until the answer is 'No' or 'Cancel'. This is what i have:

answer = questdlg('Do you want to make another measurement?');
while answer == 'Yes'
    imshow(image)
    [x,y] = getpts();
    measurement = pdist([x.';y.']);
    close
    answer = questdlg('Do you want to make another measurement?');
end

But I get an error the 'Matrix dimensions must agree'. I'm assuming that the way I'm looping is incorrect. Can anyone see the problem with the loop? It only gives an error when I select 'No' or 'Cancel'.

Answer 1

[Fangjun Jiang]

Use isequal(answer,'Yes') or strcmp(answer,'Yes')

'Yes'=='No' will cause the problem.

[Carolyn]

Thanks!

Answer 2

[Walter Roberson]

With r2017a or later you can also use

answer == "Yes"