AcDbTable::numContents

int numContents(
    int nRow, 
    int nCol
) const;

Returns the number of contents in the specified cell.

Parameters	Description
nRow	Input row index. It should be more than or equal to 0 and less than the number of rows.
nCol	Input column index. It should be more than or equal to 0 and less than the number of columns.