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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 ...
For example, given int i = 1; j = 2;, the result of max(i,j) is 2. If a and b were only evaluated once, the result of max(i++,j++) would be the same, but with double evaluation the result is 3. Hidden order of operation. Failure to bracket arguments can lead to unexpected results. For example, a macro to double a value might be written as:
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 ...
For #include guards to work properly, each guard must test and conditionally set a different preprocessor macro. Therefore, a project using #include guards must work out a coherent naming scheme for its include guards, and make sure its scheme doesn't conflict with that of any third-party headers it uses, or with the names of any globally visible macros.
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 ...
gpp is another general macro processor written by Denis Auroux. It resembles a C preprocessor, but has more general semantics and allows for customized syntax (for instance, TeX, XHTML, and Prolog-like scripts are definable). [8] M5 1999 m5 is a general-purpose macro processor written by William A. Ward, Jr.
Since ANSI C was adopted by the International Organization for Standardization, [4] the C standard library is also called the ISO C library. [5] The C standard library provides macros, type definitions and functions for tasks such as string manipulation, mathematical computation, input/output processing, memory management, and input/output.