How to calculate area

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MatLab

s = regionprops(BW5, I, {'Area','Centroid','PixelValues','BoundingBox'});
figure, imshow(BW5);
title('Standard Deviation of Regions');
hold on
for k = 1 : numObj
    s(k).StandardDeviation = std(double(s(k).PixelValues));
    text(s(k).Centroid(1),s(k).Centroid(2), ...
        sprintf('%2.1f', s(k).StandardDeviation), ...
        'EdgeColor','b','Color','r');
end
for k = 1 : numObj
    S(k)=s(k).Area;

   text(S(1),S(2), ...
       sprintf('%d', S(k)), ...
       'EdgeColor','b','Color','r');


end
hold off

when I run the code, it shows error in

text(S(1),S(2), ...
      sprintf('%d', S(k)), ...
      'EdgeColor','b','Color','r');

I think most probably I type it in a wrong way.
Can anyone help me correct it?
Thanks.

This code is basically find the area of each objects that had been detected.