C Extensions (Using the GNU Compiler Collection (GCC)) (original) (raw)

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6 Extensions to the C Language Family ¶

GNU C provides several language features not found in ISO standard C. (The -pedantic option directs GCC to print a warning message if any of these features is used.) To test for the availability of these features in conditional compilation, check for a predefined macro__GNUC__, which is always defined under GCC.

These extensions are available in C and Objective-C. Most of them are also available in C++. See Extensions to the C++ Language, for extensions that apply only to C++.

Some features that are in ISO C99 but not C90 or C++ are also, as extensions, accepted by GCC in C90 mode and in C++.

• Additional Numeric Types
• Array, Union, and Struct Extensions
• Named Address Spaces
• Attributes Specific to GCC
• Pragmas Accepted by GCC
• Thread-Local Storage
• OpenMP
• OpenACC
• An Inline Function is As Fast As a Macro
• When is a Volatile Object Accessed?
• How to Use Inline Assembly Language in C Code
• Other Extensions to C Syntax
• Extensions to C Semantics