Editing C preprocessor (section)

{{Short description|Text processor used with C and C++ and other programming tools}}
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The '''C preprocessor''' ('''CPP''') is a [[text file]] [[preprocessor|processor]] that is used with [[C (programming language)|C]], [[C++]] and other [[programming tool]]s. The preprocessor provides for file inclusion (often [[header files]]), [[macro (computer science)|macro]] expansion, [[conditional compilation]], and line control. Although named in association with C and used with C, the preprocessor capabilities are not inherently tied to the C language. It can and is used to process other kinds of files.<ref>[https://gist.github.com/djedr/7d21eac05ce2bbbca29b29d532a1fbe4 General-purpose text preprocessing with the C preprocessor. Featuring JavaScript]</ref>

C, C++, and [[Objective-C]] compilers provide a preprocessor capability, as it is required by the definition of each language. Some compilers provide extensions and deviations from the target language standard. Some provide options to control standards compliance. For instance, the GNU C preprocessor can be made more standards compliant by supplying certain command-line flags.<ref name="gnu-cpp-overview">
{{cite web
|title=The C Preprocessor: Overview
|url=https://gcc.gnu.org/onlinedocs/cpp/Overview.html
|access-date=17 July 2016
}}</ref>

The [[C Sharp (programming language)|C#]] programming language also allows for directives, even though they cannot be used for creating macros, and is generally more intended for features such as conditional compilation.<ref>{{cite web|url=https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/preprocessor-directives|title=C# preprocessor directives|date=14 January 2022 |publisher=Microsoft}}</ref> C# seldom requires the use of the directives, for example code inclusion does not require a preprocessor at all (as C# relies on a package/namespace system like Java, no code needs to be "included").

The [[Haskell]] programming language also allows the usage of the C preprocessor, which is invoked by writing <syntaxhighlight lang="Haskell" inline>{-# LANGUAGE CPP #-}</syntaxhighlight> at the top of the file. The accepted preprocessor directives align with those in standard C/C++.

Features of the preprocessor are encoded in [[source code]] as [[Directive (programming)|directives]] that start with <code>#</code>.

Although C++ source files are often named with a <code>.cpp</code> extension, that is an abbreviation for "C plus plus"; not C preprocessor.