C++ FAQ Celebrating Twenty-One Years of the C++ FAQ!!!
(Click here for a personal note from Marshall Cline.)
Section 28:
[28.2] Should I learn C before I learn OO/C++?

Don't bother.

If your ultimate goal is to learn OO/C++ and you don't already know C, reading books or taking courses in C will not only waste your time, but it will teach you a bunch of things that you'll explicitly have to un-learn when you finally get back on track and learn OO/C++ (e.g., malloc(), printf(), unnecessary use of switch statements, error-code exception handling, unnecessary use of #define macros, etc.).

If you want to learn OO/C++, learn OO/C++. Taking time out to learn C will waste your time and confuse you.