There are two reasons you could want to use a tree:
You want to mirror the problem using a tree-like structure:
For this we have boost graph library
Or you want a container that has tree like access characteristics
For this we have
std::map
(andstd::multimap
)std::set
(andstd::multiset
)
Basically the characteristics of these two containers is such that they practically have to be implemented using trees (though this is not actually a requirement).
See also this question:
C tree Implementation