c++ - Opencv Array of strings? -

i want classify images using svm , need give labels, in matlab do:

labels = {'ball';'plane';'person'};   

how make in opencv? following code failed:

mat_<string> m (3,1); m.at<string>(0) = "ball"; m.at<string>(1) = "plane";  m.at<string>(2) = "person";