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The type-generic macros that correspond to a function that is defined for only real numbers encapsulates a total of 3 different functions: float, double and long double variants of the function. The C++ language includes native support for function overloading and thus does not provide the <tgmath.h> header even as a compatibility feature.
A parameterized macro is a macro that is able to insert given objects into its expansion. This gives the macro some of the power of a function. As a simple example, in the C programming language, this is a typical macro that is not a parameterized macro, i.e., a parameterless macro: #define PI 3.14159
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 ...
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."
After this, each invocation of the va_arg macro yields the next argument. 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.
The C library functions, including the ISO C standard ones, are widely used by programs, and are regarded as if they were not only an implementation of something in the C language, but also de facto part of the operating system interface. Unix-like operating systems generally cannot function if the C library is erased.
Examples of such lists particularly include initialization of arrays, in concert with declarations of enumeration constants and function prototypes; generation of statement sequences and switch arms; etc. Usage of X macros dates back to the 1960s. [1] It remains useful in modern-day C and C++ programming languages, but remains relatively ...
C's offsetof() macro is an ANSI C library feature found in stddef.h. It evaluates to the offset (in bytes) of a given member within a struct or union type, an expression of type size_t . The offsetof() macro takes two parameters , the first being a structure or union name, and the second being the name of a subobject of the structure/union that ...