Extensions to the C++ Language

The GNU compiler provides these extensions to the C++ language (and you can also use most of the C language extensions in your C++ programs). If you want to write code that checks whether these features are available, you can test for the GNU compiler the same way as for C programs: check for a predefined macro __GNUC__. You can also use __GNUG__ to test specifically for GNU C++ (see Predefined Macros).

• Where G++ puts inlines, vtables and such.
• Declaring multiple function versions.
• Strong using-directives for namespace association.
• Compiler support for type traits
• Tweaking exception handling to work with Java.
• Things will disappear from G++.
• Compatibilities with earlier definitions of C++.

• When is a Volatile C++ Object Accessed?
• Restricting Pointer Aliasing
• Vague Linkage
• C++ Interface and Implementation Pragmas
• Where’s the Template?
• Extracting the Function Pointer from a Bound Pointer to Member Function
• C++-Specific Variable, Function, and Type Attributes
• Function Multiversioning
• Namespace Association
• Type Traits
• Java Exceptions
• Deprecated Features
• Backwards Compatibility