Comment (computer programming): Difference between revisions

Revision as of 14:35, 11 January 2025

Revision as of 14:42, 11 January 2025

Line 471:

</syntaxhighlight>

====Double dash====

A relatively loose collection of languages use <code>--</code> for a single line comment. Notable languages include: [[Ada (programming language)|Ada]], and[[Eiffel (programming language)|Eiffel]], [[Haskell (programming language)|Haskell]], [[Lua (programming language)|Lua]], [[SQL]] and [[VHDL]]. Block comment support varies. An example in Ada:

<syntaxhighlight lang="ada">

Line 523:

\end{code}

Here more explanation using \LaTeX{} markup

</syntaxhighlight>

====Block in Lua====

ALua commonsupports techniqueblock tocomments commentdelimited outby a<code>--[[</code> segment ofand <code,>]]</code><ref>{{Cite web|url=http://www.lua.org/pil/1.3.html|title=Programming in Lua 1.3|website=www.Lua.org|access-date=2017-11-08}}</ref> isFor to enclose the code between <code>--[[</code> andexample:

<syntaxhighlight lang="lua">

--[[A multi-line

long comment

]]

</syntaxhighlight>

Line 635 ⟶ 644:

end program

</syntaxhighlight>

====Lua====

[[Lua (programming language)|Lua]] uses double-hyphens, <code>--</code>, for single line comments in a similar way to [[Ada (programming language)|Ada]], [[Eiffel (programming language)|Eiffel]], [[Haskell (programming language)|Haskell]], [[SQL]] and [[VHDL]] languages. Lua also has block comments, which start with <code>--[[</code> and run until a closing <code>]]</code> For example:

<syntaxhighlight lang="lua">

--[[A multi-line

long comment

]]

print(20) -- print the result

</syntaxhighlight>

A common technique to comment out a segment of code,<ref>{{Cite web|url=http://www.lua.org/pil/1.3.html|title=Programming in Lua 1.3|website=www.Lua.org|access-date=2017-11-08}}</ref> is to enclose the code between <code>--[[</code> and

<code>--]]</code>, as below:

<syntaxhighlight lang="lua">

--[[

print(10)

--]]

-- no action (commented out)

</syntaxhighlight>

In this case, it's possible to enable the code for use (uncomment-out) by adding a single hyphen to the first line:

<syntaxhighlight lang="lua">

---[[

print(10)

--]]

--> 10

</syntaxhighlight>

The <code>--[[</code> in the first line starts a long comment, and the two hyphens in the last line

are still inside that comment. In the second example, the sequence <code>---[[</code> starts an ordinary, single-line

comment, so that the first and the last lines become independent comments. In this case, the <code>print</code> is

outside comments. In this case, the last line becomes an independent comment, as it starts with <code>--</code>.

====MATLAB====