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Directives are sometimes part of the formal grammar |
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{{short description|Language construct that specifies how a compiler should process its input}}
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. Directives are not{{disputed inline|Directives are part of the language in many cases|reason=In many assemblers directives are part of the grammar.}} part of the [[Formal grammar|grammar]] of a [[programming 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 signaling|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.
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