Editing Parameter (section)

==Computer programming==
{{Main|Parameter (computer programming)}}
In [[computer programming]], two notions of [[parameter (computer programming)|parameter]] are commonly used, and are referred to as [[Parameter (computer programming)#Parameters and arguments|parameters and arguments]]—or more formally as a '''formal parameter''' and an '''actual parameter'''.

For example, in the definition of a function such as
: y = ''f''(''x'') = ''x'' + 2,
''x'' is the ''formal parameter'' (the ''parameter'') of the defined function.

When the function is evaluated for a given value, as in
:''f''(3): or,  ''y'' = ''f''(3) = 3 + 2 = 5,
3 is the ''actual parameter'' (the ''argument'') for evaluation by the defined function; it is a given value (actual value) that is substituted for the ''formal parameter'' of the defined function. (In casual usage the terms ''parameter'' and ''argument'' might inadvertently be interchanged, and thereby used incorrectly.)

These concepts are discussed in a more precise way in [[functional programming]] and its foundational disciplines, [[lambda calculus]] and [[combinatory logic]]. Terminology varies between languages; some computer languages such as [[C (programming language)|C]] define parameter and argument as given here, while [[Eiffel (programming language)|Eiffel]] uses an [[Parameter (computer programming)#Alternative convention in Eiffel|alternative convention]].