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A variadic macro is a feature of some computer programming languages, especially the C preprocessor, whereby a macro may be declared to accept a varying number of arguments. Variable-argument macros were introduced in 1999 in the ISO/IEC 9899:1999 ( C99 ) revision of the C language standard, and in 2011 in ISO/IEC 14882:2011 ( C++11 ) revision ...
This example aims to improve the readability of the X macro usage by: Prefix the name of the macro that defines the list with "FOR_". Pass name of the worker macro into the list macro. This both avoids defining an obscurely named macro (X), and alleviates the need to undefine it. Use the syntax for variadic macro arguments "..." in the worker ...
Many compilers define additional, non-standard macros. A common reference for these macros is the Pre-defined C/C++ Compiler Macros project, which lists "various pre-defined compiler macros that can be used to identify standards, compilers, operating systems, hardware architectures, and even basic run-time libraries at compile-time."
The first argument to va_arg is the va_list and the second is the type of the next argument passed to the function. As the last step, the va_end macro must be called on the va_list before the function returns. Note that it is not required to read in all the arguments. C99 provides an additional macro, va_copy, which can duplicate the state of a ...
Variadic functions no longer need a named argument before the ellipsis and the va_start macro no longer needs a second argument nor does it evaluate any argument after the first one if present. [43] Add C++11 style attribute syntax [44] using double square brackets [[]]. In addition to C++11 attributes listed below, add new attributes:
The variadic template feature of C++ was designed by Douglas Gregor and Jaakko Järvi [1] [2] and was later standardized in C++11. Prior to C++11, templates (classes and functions) could only take a fixed number of arguments, which had to be specified when a template was first declared.
The basic variadic facility in C++ is largely identical to that in C. The only difference is in the syntax, where the comma before the ellipsis can be omitted. C++ allows variadic functions without named parameters but provides no way to access those arguments since va_start requires the name of the last fixed argument of the function.
C99 introduced macros with a variable number of arguments. [ 5 ] C++11 included the C99 preprocessor, [ 6 ] and also introduced templates with a variable number of arguments .