VC++6 : Mix C and C++ header rule

Its just my hypotesis . C++ need  “filename.h”  in header file while  C  can accept <filename.h>

How can we mix code that contain C and C++

My best solution until now is having 2 include file. One with <filename.h>  format and one with  “filename.h ” although

the content is exactly same

Any better idea?