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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 ...
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
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 ...
The C preprocessor (CPP) is a text file processor that is used with C, C++ and other programming tools. The preprocessor provides for file inclusion (often header files), macro expansion, conditional compilation, and line control. Although named in association with C and used with C, the preprocessor capabilities are not inherently tied to the ...
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.
A common example from computer programming is the processing performed on source code before the next step of compilation. In some computer languages (e.g., C and PL/I) there is a phase of translation known as preprocessing. It can also include macro processing, file inclusion and language extensions.
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 ...
Translation units define a scope, roughly file scope, and functioning similarly to module scope; in C terminology this is referred to as internal linkage, which is one of the two forms of linkage in C. Names (functions and variables) declared outside of a function block may be visible either only within a given translation unit, in which case they are said to have internal linkage – they are ...