Comment (computer programming): Difference between revisions

Revision as of 12:46, 11 January 2025

Revision as of 13:04, 11 January 2025

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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]]. The list ofNotable languages that use this syntax is long but a few of the more notable include: C, C++, [[C# (programming language)|C#]], [[Java (programming language)|Java]], and [[Javascript]]. For example:

<syntaxhighlight lang="c">

Line 359:

</syntaxhighlight>

====RScripting====

A pattern in many [[scripting language]]s is to delimit a line comment with <code>#</code> and provide no support for a block comment. Notable languages include: [[Bash (Unix shell)|Bash]], [[Python (programming language)|Python]] and [[R (programming language)|R]].

An example in R:

<syntaxhighlight lang="R">

# This is a comment

print("This is not a comment") # This is another comment

</syntaxhighlight>

=====In Python=====

Although Python does not provide for block comments<ref name=triple>{{cite web |url=https://www.tutorialdocs.com/tutorial/python3/python3-basic-syntax.html |title=Python 3 Basic Syntax |access-date=25 February 2019 |quote=Triple quotes are treated as regular strings with the exception that they can span multiple lines. By regular strings I mean that if they are not assigned to a variable they will be immediately garbage collected as soon as that code executes. hence are not ignored by the interpreter in the same way that #a comment is. |archive-date=19 August 2021 |archive-url=https://web.archive.org/web/20210819164828/https://www.tutorialdocs.com/tutorial/python3/python3-basic-syntax.html |url-status=dead }}</ref> but a bare [[string literal]] represented by a triple-quoted string can be andis often is used for this purpose.<ref>[https://twitter.com/gvanrossum/status/112670605505077248 "Python tip: You can use multi-line strings as multi-line comments"], 11 September 2011, Guido van Rossum</ref><ref name=triple/> In the examples below, the triple double-quoted strings act like comments, but are also treated as [[docstring]]s:

<syntaxhighlight lang="python">

"""

At the top of a file, this is the module docstring

"""

class MyClass:

"""The class'sClass docstring"""

def my_method(self):

"""The method'sMethod docstring"""

</syntaxhighlight>

===By language===

Line 643 ⟶ 669:

</syntaxhighlight>

Instead of a regular block commenting construct, Perl uses [[Plainliterate Old Documentationprogramming]], a[[Plain markupOld languageDocumentation|plain forold [[literatedocumentation programming(POD)]], markup.<ref>

{{cite web

| title = perlpod – the Plain Old Documentation format

| url = http://perldoc.perl.org/perlpod.html|access-date=2011-09-12

}}

</ref> forFor instanceexample:<ref>

{{cite web

| title = Pod::ParseUtils – helpers for POD parsing and conversion

Line 674 ⟶ 700:

return $self;

}

</syntaxhighlight>

====R====

[[R (programming language)|R]] only supports inline comments started by the hash (#) character.

<syntaxhighlight lang="R">

# This is a comment

print("This is not a comment") # This is another comment

</syntaxhighlight>

Line 748 ⟶ 767:

Write-Host "Goodbye, world!"

</syntaxhighlight>

====Python====

Line comments in [[Python (programming language)|Python]] are delimiated by the hash (#) character. For example:

<syntaxhighlight lang="python">

# This program prints "Hello World" to the screen

print("Hello World!") # Note the new syntax

</syntaxhighlight>

Python does not provide for block comments<ref name=triple>{{cite web |url=https://www.tutorialdocs.com/tutorial/python3/python3-basic-syntax.html |title=Python 3 Basic Syntax |access-date=25 February 2019 |quote=Triple quotes are treated as regular strings with the exception that they can span multiple lines. By regular strings I mean that if they are not assigned to a variable they will be immediately garbage collected as soon as that code executes. hence are not ignored by the interpreter in the same way that #a comment is. |archive-date=19 August 2021 |archive-url=https://web.archive.org/web/20210819164828/https://www.tutorialdocs.com/tutorial/python3/python3-basic-syntax.html |url-status=dead }}</ref> but a bare [[string literal]] represented by a triple-quoted string can be and often is used for this purpose.<ref>[https://twitter.com/gvanrossum/status/112670605505077248 "Python tip: You can use multi-line strings as multi-line comments"], 11 September 2011, Guido van Rossum</ref><ref name=triple/> In the examples below, the triple double-quoted strings act like comments, but are also treated as [[docstring]]s:

<syntaxhighlight lang="python">

"""

Assuming this is file mymodule.py, then this string, being the

first statement in the file, will become the "mymodule" module's

docstring when the file is imported.

"""

class MyClass:

"""The class's docstring"""

def my_method(self):

"""The method's docstring"""

def my_function():

"""The function's docstring"""

</syntaxhighlight>