Constants of C/C++, what type of constants you are talking about, as of it is well know, that constants defined in the both language are the same as we can import the headers of C in the C++. For example, C header <math.h> is used in C++ as <cmath> So the constants are same.
Like the constant M_PI defined in MATH.H
And if you are talking about, predefined data structures provided as C++-STL or variables then I should add that that the revisions C-14 and C++-14 have been done, and you should always remember that what C has, C++ will surely has.
C++ has anonymous and named lambda functions, that can be used to defined variables, then it has AUTO keyword to automatically predict the type of variable.