Contents|Index|Previous|Next Extensions to the C language family   GNU C provides several language features not found in ANSI standard C. (The option, ‘-pedantic’, directs GNU CC 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 GNU CC. These extensions are available in C and Objective C. Most of the extensions are also available in C++. See Extensions to the C++ language for extensions that apply only to C++. See the following documentation for more specific discussion regarding extensions to the C language family. Statements and declarations in expressions Locally declared labels Labels as values Nested functions Constructing function calls Naming an expression’s type Referring to a type with typeof Generalized Lvalues Conditionals with omitted operands Double-word integers Complex numbers Arrays of length zero Arrays of variable length Macros with variable number of arguments Non-Lvalue arrays may have subscripts Arithmetic on void- and function-pointers Non-constant initializers Constructor expressions Labeled elements in initializers Case ranges Cast to a union yype Declaring attributes of functions Prototypes and old-style function definitions Compiling functions for interrupt calls C++ style comments Dollar signs in identifier names The ESC character in constants Inquiring on alignment of types or variables Specifying attributes of variables Specifying attributes of types An inline function is as fast as a macro Assembler instructions with C expression operands Constraints for asm operands Simple constraints Multiple alternative constraints Constraint modifier characters Constraints for particular machines Controlling names used in assembler code Variables in specified registers Defining global register variables Specifying registers for local variables Alternate keywords Incomplete enum types Function namers as strings Getting the return or frame address of a function Top|Contents|Index|Previous|Next   <