To Get Dimensions of an AutoCad Drawing

Hi all,

         This is my First post to this forum....My problem in hand is that i need to get the values of  dimension of  an auto cad drawing (normally in dwg or dxf format) thruogh my VB.Net application and they are usually 2D drawings... for example, if  I have a design of  a floor of a bulding describing the  length and breadth of each room,which is in autocad drawing, i need to get this Length and Breadth and finally i ve to calculate the area of the entire floor  

         As I dont have a clue in Auto Cad,any help will be greatly appreciated