Here''s the scoop:

dynamic_cast - for casting down an inheritance heirarchy. For example, you have a base class ptr and you want to know if it is a particular derived class, you use dynamic_cast, assuming you have RTTI and at least 1 virtual function ( which you should as in an inheritance heirarchy you should always make sure destructors are declared virtual )

static_cast - similar to the "C-style" cast - typically you''ll use this to convert longs to shorts or integer types to enums and stuff like that

const_cast - removes or adds const or volatile-ness - generally you should avoid const_cast as removing const-ness is usually akin to removing some of the safety you''ve designed into your classes. One use can be though if you have a const reference to an object that must return a portion of its representation to be placed into an existing API which expects a non-const ptr value, then you can use it there. but it may cause headaches

reinterpret_cast - converts pointers to integers and vice versa, and function ptrs to object ptrs and other scary stuff - generally you can probably avoid this

The February 2000 issue of C++ Report has an article on C++ cast operators - you may want to check it out