Want to know structure where Variable name , Value , address , type etc. is stored

Hi,
    I want to design a small debugger . Not a complete debugger , just
want to display value of variables of C program.
    In our simple C program whatever variables we declared . Few
things are always associated with it like variable type,variable name,
its address ,value of that variable.
    Anyone who knows how ddd gets these values ? And If I want to do
that how can I do it?

Thanks...

-- 
...Swapnil