1) C does not have OOPS feature such as polymorphism,data hiding and others,that's why C++ is developed.It is structured programming language that cannot represent real world object and cannot provide security.
2) There is no run-time checking in C language.
3) There is no strict type checking (for ex: we can pass an integer value for the floating data type).
4) C doesn't have the concept of namespace.
5) C doesn't have the concept of constructors and destructors.
6) As the program extends it is very difficult to fix the bugs.
Comment for any doubts.....