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The preprocessor provides some macro definitions automatically. The C standard specifies that __FILE__ expands to the name of the file being processed and __LINE__ expands to the number of the line that contains the directive. The following macro, DEBUGPRINT, formats and prints a message with the file name and line number.
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 #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.
The assert macro implements runtime assertion. If the expression within it is false, the macro will print a message to stderr and call abort(), defined in stdlib.h.The message includes the source filename and the source line number from the macros __FILE__ and __LINE__, respectively. [2]
In computer science, a preprocessor (or precompiler) [1] is a program that processes its input data to produce output that is used as input in another program. The output is said to be a preprocessed form of the input data, which is often used by some subsequent programs like compilers .
A translation unit is the output of the C preprocessor – a source file after it has been preprocessed. Preprocessing notably consists of expanding a source file to recursively replace all #include directives with the literal file declared in the directive (usually header files , but possibly other source files); the result of this step is a ...
In C and C++, a header file is a source code file that allows programmers to separate elements of a codebase – often into reusable, logically-related groupings. A header file declares programming elements such as functions, classes, variables, and preprocessor macros. A header file allows the programmer to use programming elements in multiple ...
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