well i beleive that C is nothing got to do with C++ learning .
at the basic level u will find both of them are same (if u r working on a turbo c/c++ complier). only little differences in syntax.....
but if u get used to c++ notation u will find c notations a bit uncomfortable as u will have to be more explicit in usiing them.
even then it doesnt make a very huge significant difference though.
the main concept is to get familiar with the programing methodology which will be similar in all and u can only master it by experience