The method GetClassCounts returns the number of data points for each class. After calling GetClassCounts the array ClsCnt contains the class counts (including class 0). The ClsCnt parameter is automatically resized to 1+MAXDSETCLASSES.
Please note that the class zero - which is actually not a class but an indicator that the data point has no class - is counted as well. The valid indices of array ClsCnt are thus running from 0 to NClasses. Class counts above NClasses up to MAXDSETCLASSES are always zero.