All of our C++ headers use a .h extension. Eclipse thinks these are C headers and flags them with lots of syntax errors on things like classes and namespaces.
I've tried to change the file type association from:
Preferences > C/C++ > File types
but it's "locked".
Interestingly, "*.h" is associated with both C and C++ headers, but it seems to be using C. How can I get Eclipse to treat .h files as C++?
Try creating a new project and specify your source area as the location. However, be sure you select C++ project (I usually use the makefile option). This is all you should have to do in order to make the parser recognize C++ syntax.
来源：https://stackoverflow.com/questions/226402/make-eclipse-treat-h-file-as-c