Directive (programming): Difference between revisions

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{{short description|Language construct that specifies how a compiler should process its input}}

{{Refimprove|date=December 2013}}

In [[computer programming]], a '''directive''' or '''pragma''' (from "pragmatic") is a [[language construct]] that specifies how a [[compiler]] (or other [[Translator (computing)|translator]]) should process its input. Depending on the [[programming language]], directives may or may not be part of the [[Formal grammar|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.

In some cases directives specify global behavior, while in other cases they only affect a local section, such as a block of programming code. In some cases, such as some C programs, directives are optional compiler hints, and may be ignored, but normally they are prescriptive, and must be followed. However, a directive does not perform any action in the language itself, but rather only a change in the behavior of the compiler.

This term could be used to refer to proprietary third -party tags and commands (or markup) embedded in code that result in additional executable processing that extend the existing compiler, assembler and language constructs present in the development environment. The term "directive" is also applied in a variety of ways that are similar to the term ''command''.

==The C preprocessor==