Editing Asterisk (section)

====Programming languages====
Many [[programming language]]s and [[calculator]]s use the asterisk as a symbol for [[multiplication]]. It also has a number of special meanings in specific languages, for instance:
* In some languages such as [[C (programming language)|C]], [[C++]], and [[Go (programming language)|Go]], the asterisk is used to [[dereference]] or declare a [[pointer (computer programming)|pointer]] variable.
* In [[Common Lisp]], the names of [[global variable]]s are conventionally set off with asterisks, <code>*LIKE-THIS*</code>.
* In the [[Ada (programming language)|Ada]], [[Fortran]], [[Perl]], [[Python (programming language)|Python]], [[Ruby (programming language)|Ruby]], some dialects of [[Pascal programming language|Pascal]], and many others, a double asterisk is used to signify [[exponentiation]]: <code>5**3</code> is 5<sup>3</sup> = 125.
* In [[Perl]], the asterisk is used to refer to the ''[[typeglob]]'' of all variables with a given name.
* In [[Ruby (programming language)|Ruby]] and [[Python (programming language)|Python]], the asterisk has two specific uses. First, the unary * operator applied to a list object inside a function call will expand that list into the positional arguments of the function call. Second, a parameter preceded by * {{anchor|args}}in the parameter list in a function definition will result in any extra positional parameters being aggregated into a [[tuple]] (Python) or [[array data type|array]] (Ruby), and likewise a parameter preceded by ** {{Anchor|kwargs}} will result in any extra [[named parameter|keyword parameters]] being aggregated into a [[associative array|dictionary]] (Python) or [[associative array|hash]] (Ruby):
<syntaxhighlight lang="python">def function1(a, b, c, d):
    print(a, b, c, d)
    
def function2(first, *args):
    # args will be a tuple
    # the name 'args' is convention: it may be any parameter name
    print(args)
    
def function3(first, **kwargs):
    # kwargs will be a dict
    # the name 'kwargs' is convention: it may be any parameter name
    print(kwargs)

function1(1, 2, 3, 4) # prints 1 2 3 4
function1(*[1, 2, 3, 4]) # prints 1 2 3 4
function1(**{"a": 5, "b": 6, "c": 7, "d": 8}) # prints 5 6 7 8

function2(1, 2, 3, 4) # prints (2, 3, 4), 1 is not part of args
function2(99) # prints (), unfilled *parameter will be ()

function3(0, e=3, f=9) # prints {'e': 3, 'f': 9}, 0 is not part of kwargs
function3(0) # prints {}, unfilled **parameter will be {}</syntaxhighlight>
* In [[APL (programming language)|APL]], the asterisk represents the [[Exponential function|exponential]] and [[exponentiation]] functions, with <code>*X</code> representing <var>e</var><sup><var>X</var></sup>, and <code>Y*X</code> representing <var>Y</var><sup><var>X</var></sup>.
* In IBM [[Job Control Language]], the asterisk has various functions, including in-stream data in the DD statement, the default print stream as <code>SYSOUT=*</code>, and as a self-reference in place of a procedure step name to refer to the same procedure step where it appears.
* In [[Haskell (programming language)|Haskell]], the asterisk represents the set of well-formed, fully applied types; that is, a 0-ary ''kind'' of types.

=====Comments in programming languages=====
{{Main article|block comments}}
In the [[B (programming language)|B programming language]] and languages that borrow syntax from it, such as [[C (programming language)|C]], [[PHP]], [[Java (software platform)|Java]], or [[C Sharp (programming language)|C#]], comments in the [[source code]] (for information to people, ignored by the [[compiler]]) are marked by an asterisk combined with the slash:

<syntaxhighlight lang="c#">
 /* This section displays message if user input was not valid
    (comment ignored by compiler) */
</syntaxhighlight>

[[CSS]] also uses this comment format:<syntaxhighlight lang="css">
body {
  /* This ought to make the text more readable for far-sighted people */
  font-size: 24pt;
}
</syntaxhighlight>

Some [[Pascal (programming language)|Pascal]]-like programming languages, such as [[Object Pascal]], [[Modula-2]], [[Modula-3]], and [[Oberon (programming language)|Oberon]], and other languages such as [[ML (programming language)|ML]], [[Wolfram Language]] ([[Mathematica]]), [[AppleScript]], [[OCaml]], [[Standard ML]], and [[Maple (software)|Maple]], use an asterisk combined with a parenthesis:

<syntaxhighlight lang="Applescript">
 (* Do not change this variable - it is used later
    (comment ignored by compiler) *)
</syntaxhighlight>

Each computing language has its own way of handling comments; {{code|/* ... */}} and similar notations are not universal.