In computing, a compiler is a computer program that translates computer code written in one programming language into another language. The name "compiler" is primarily used for programs that translate source code from a high-level programming language to a low-level programming language to create an executable program.
C is a general-purpose computer programming language. It was created in the 1970s by Dennis Ritchie, and remains very widely used and influential. By design, C's features cleanly reflect the capabilities of the targeted CPUs. It has found lasting use in operating systems, device drivers, and protocol stacks, but its use in application software has been decreasing. C is commonly used on computer architectures that range from the largest supercomputers to the smallest microcontrollers and embedded systems.
Common Lisp (CL) is a dialect of the Lisp programming language, published in American National Standards Institute (ANSI) standard document ANSI INCITS 226-1994 (S20018). The Common Lisp HyperSpec, a hyperlinked HTML version, has been derived from the ANSI Common Lisp standard.
In computer programming, the scope of a name binding is the part of a program where the name binding is valid; that is, where the name can be used to refer to the entity. In other parts of the program, the name may refer to a different entity, or to nothing at all. Scope helps prevent name collisions by allowing the same name to refer to different objects – as long as the names have separate scopes. The scope of a name binding is also known as the visibility of an entity, particularly in older or more technical literature—this is in relation to the referenced entity, not the referencing name.
In computer science, a preprocessor 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. The amount and kind of processing done depends on the nature of the preprocessor; some preprocessors are only capable of performing relatively simple textual substitutions and macro expansions, while others have the power of full-fledged programming languages.
The C preprocessor is the macro preprocessor for several computer programming languages, such as C, Objective-C, C++, and a variety of Fortran languages. The preprocessor provides inclusion of header files, macro expansions, conditional compilation, and line control.
In computer programming, a global variable is a variable with global scope, meaning that it is visible throughout the program, unless shadowed. The set of all global variables is known as the global environment or global state. In compiled languages, global variables are generally static variables, whose extent (lifetime) is the entire runtime of the program, though in interpreted languages, global variables are generally dynamically allocated when declared, since they are not known ahead of time.
In the C and C++ programming languages, an inline function is one qualified with the keyword inline; this serves two purposes:
- It serves as a compiler directive that suggests that the compiler substitute the body of the function inline by performing inline expansion, i.e. by inserting the function code at the address of each function call, thereby saving the overhead of a function call. In this respect it is analogous to the
register storage class specifier, which similarly provides an optimization hint. - The second purpose of
inline is to change linkage behavior; the details of this are complicated. This is necessary due to the C/C++ separate compilation + linkage model, specifically because the definition (body) of the function must be duplicated in all translation units where it is used, to allow inlining during compiling, which, if the function has external linkage, causes a collision during linking. C and C++ resolve this in different ways.
In software development, distcc is a tool for speeding up compilation of source code by using distributed computing over a computer network. With the right configuration, distcc can dramatically reduce a project's compilation time.
In computer programming, a directive or pragma is a language construct that specifies how a compiler should process its input. Depending on the programming language, directives may or may not be part of the grammar of the language and may vary from compiler to compiler. They can be processed by a preprocessor to specify compiler behavior, or function as a form of in-band parameterization.
The One Definition Rule (ODR) is an important rule of the C++ programming language that prescribes that classes/structs and non-inline functions cannot have more than one definition in the entire program and template and types cannot have more than one definition by translation unit. It is defined in the ISO C++ Standard 2003, at section 3.2. Some other programming languages have similar but differently defined rules towards the same objective.
In the C and C++ programming languages, an #include guard, sometimes called a macro guard, header guard or file guard, is a particular construct used to avoid the problem of double inclusion when dealing with the include directive.
In computer programming, a precompiled header (PCH) is a header file that is compiled into an intermediate form that is faster to process for the compiler. Usage of precompiled headers may significantly reduce compilation time, especially when applied to large header files, header files that include many other header files, or header files that are included in many translation units.
In the C and C++ programming languages, #pragma once is a non-standard but widely supported preprocessor directive designed to cause the current header file to be included only once in a single compilation. Thus, #pragma once serves the same purpose as include guards, but with several advantages, including less code, avoidance of name clashes, and sometimes improvement in compilation speed. On the other hand, #pragma once is not necessarily available in all compilers and its implementation is tricky and might not always be reliable.
This comparison of programming languages compares the features of language syntax (format) for over 50 computer programming languages.
Single compilation unit (SCU) is a computer programming technique for the C and C++ languages, which reduces compilation time for programs spanning multiple files. Specifically, it allows the compiler to keep data from shared header files, definitions and templates, so that it need not recreate them for each file. It is an instance of program optimization. The technique can be applied to an entire program or to some subset of source files; when applied to an entire program, it is also known as a unity build.
In the C programming language, an external variable is a variable defined outside any function block. On the other hand, a local (automatic) variable is a variable defined inside a function block.
As an alternative to automatic variables, it is possible to define variables that are external to all functions, that is, variables that can be accessed by name by any function. Because external variables are globally accessible, they can be used instead of argument lists to communicate data between functions. Furthermore, because external variables remain in existence permanently, rather than appearing and disappearing as functions are called and exited, they retain their values even after the functions that set them have returned.
Many programming languages and other computer files have a directive, often called include, import, or copy, that causes the contents of the specified file to be inserted into the original file. These included files are called header files or copybooks. They are often used to define the physical layout of program data, pieces of procedural code, and/or forward declarations while promoting encapsulation and the reuse of code or data.
ECPG is the standard, in the PostgreSQL database built-in, client programming interface for embedding SQL in programs written in the C programming language. It provides the option for accessing the PostgreSQL database directly from the C code in the application, using SQL commands.
In software engineering, a unity build is a method used in C and C++ software development to speed up the compilation of projects by combining multiple translation units into a single one, usually achieved by using include directives to bundle multiple source files into one larger file.
