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Language Extensions
3.3 C99 language features available in C++ and C90
The compiler supports numerous extensions to the ISO C++ standard and to the C90
language, for example, function prototypes that override old-style non prototype
definitions.
These extensions are available if:
• the source language is C++ and you are compiling in non strict mode
• the source language is C90 and you are compiling in non strict mode.
These extensions are not available if:
• the source language is C++ and the compiler is restricted to compiling strict C90
using the --strict compiler option.
• the source language is C90 and the compiler is restricted to compiling strict
Standard C using the --strict compiler option.
Note
Language features of Standard C, for example long long integers, might be similar to
the language extensions described in this section. Such features continue to remain
available if you are compiling strict standard C++ or strict C90 using the --strict
compiler option.
3.3.1 Variadic macros
In C90 and C++ you can declare a macro to accept a variable number of arguments.
The syntax for declaring a variadic macro in C90 and C++ follows the C99 syntax for
declaring a variadic macro, unless the option --gnu is selected. If the option --gnu is
specified, the syntax follows GNU syntax for variadic macros.
Example
#define debug(format, ...) fprintf (stderr, format, __VA_ARGS__)
void variadic_macros(void)
{
debug ("a test string is printed out along with %x %x %x\n", 12, 14, 20);
}
See also
• --gnu on page 2-44
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