Comment (computer programming): Difference between revisions

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| publisher=Cambridge University Press

| isbn=978-1-397-80521-8

}}</ref> Examples include [[Javadoc]], [[Ddoc]], [[Doxygen]], [[Visual Expert]] and [[PHPDoc]]. Forms of [[docstring]] are supported by [[Python (programming language)|Python]], [[Lisp (programming language)|Lisp]], [[Elixir (programming language)|Elixir]], and [[Clojure]].<ref>[https://clojure.github.io/clojure/clojure.core-api.html#clojure.core/defn Function definition with docstring in Clojure]</ref> [[C Sharp (programming language)|C#]], [[F Sharp (programming language)|F#]] and [[Visual Basic .NET]] implement a similar feature called "XML Comments" which are read by [[IntelliSense]] from the compiled [[.NET]] assembly.<ref>{{cite book|last=Murach|title=C# 2005|page=56}}</ref>

=== Visualization ===

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=== Extend language syntax ===

Occasionally, code that is formatted as a comment is overloaded to convey additional information to the translator, such as [[conditional comment]]scomments. As such, syntax that generally indicates a comment can actually represent program code; not comment code. Such syntax may be a practical way to maintain compatibility while adding additional functionality, but some regard such a solution as a [[kludge]].<ref>[[c2: HotComments]]</ref>

Other examples include interpreter [[Directive (programming)|directives]]:

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<syntaxhighlight lang="c">

/***************************\**

* *

* This is the comment body. *

* *

\ *****************************/

</syntaxhighlight>

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===Curly brace languages===

Many of the [[curly brace language]]s such as C, C++ and their many derivatives delimit a line comment with {{code|//}} and a block comment with {{code|/*}} and {{code|*/}}. Originally, C lacked the line comment, but it was added in [[C99]]. Notable languages include: C, C++, [[C# (programming language)|C#]], [[D (programming language)|D]], [[Java (programming language)|Java]], [[JavascriptJavaScript]] and [[Swift (programming language)|Swift]]. For example:

<syntaxhighlight lang="c">

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====APL====

[[APL (programming language)|APL]] uses <code>⍝</code> ("lamp") for a line comment. For example:

<syntaxhighlight lang="apl">

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====Fortran====

The following fixed-form [[Fortran IV]] code fragment shows that comment syntax is column-oriented. A letter <code>C</code> in the first column causes the entire line to be treated as a comment. In [[Fortran 77]], an asterisk in column 1 also indicates a comment.

<syntaxhighlight lang="fortranfixed">

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<syntaxhighlight lang="Fortran">

! A comment

program comment_test

print '(A)', 'Hello world' ! also a comment

end program

</syntaxhighlight>

Free-form Fortran, also introduced with Fortran 90, only supports this latter style of comment.

Although not a part of the Fortran Standard, many Fortran compilers offer an optional C-like [[preprocessor]] pass. This can be used to provide block comments:

<syntaxhighlight lang="Fortran">

#if 0

This is a block comment spanning

multiple lines.

#endif

program comment_test

print '(A)', 'Hello world' ! also a comment

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====OCaml====

[[OCaml]] supports nestable comments. For exmapleexample:

<syntaxhighlight lang="ocaml">

codeLine(* comment level 1(*comment level 2*)*)