(ANSI) C Reference – C Preprocessors

A look at the preprocessors that can be used in the C programming language.

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#include <filename> ->  Include library file

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#include “filename” ->  Include a user file

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#define name text ->  Replacement text

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#define name(var) text ->  Replacement macro

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#undef name ->  Un-define

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#if, #else, #endif, #elif ->  Conditional execution

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#ifdef ->  Is name defined?

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#ifndef ->  Is name not defined?

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defined(name) ->  Name defined?

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\ ->  Line continuation char

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# ->  Quoted string in replace

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## ->  Concatenate args and rescan

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