Here at the start, there are important differences between plain C and C++.

• Plain C has different header files. Their names end with .h
• Plain C has a different standard I/O library called stdio.h.
• Plain C does not have the nice C++ string library, but has a much more problematic library string.h.
• There is no namespace or using statement.
• The auto declaration is C++ only.

All plain C libraries, including stdio.h and string.h, are also available in C++. They can be included just the same, or you may use their alternate C++ names: cstdio and cstring. Usually, there is no reason to use them in C++ because the replacements are better.