Editing Truth value (section)

== Computing ==
{{see also|Implicit type conversion}}
In some programming languages, any [[Expression (computer science)|expression]] can be evaluated in a context that expects a [[Boolean data type]]. Typically (though this varies by programming language) expressions like the number [[zero]], the [[empty string]], empty lists, and [[Null pointer|null]] are treated as false, and strings with content (like "abc"), other numbers, and objects evaluate to true. Sometimes these classes of expressions are called '''falsy''' and '''truthy'''. For example, in [[Lisp (programming language)|Lisp]], [[Null pointer|nil]], the empty list, is treated as false, and all other values are treated as true. In [[C (programming language)|C]], the number 0 or 0.0 is false, and all other values are treated as true. 

In [[JavaScript]], the empty string (<code>""</code>), <code>null</code>, <code>undefined</code>, [[NaN|<code>NaN</code>]], +0, [[−0]] and <code>false</code><ref>{{cite web |url=http://www.ecma-international.org/publications/files/ECMA-ST/ECMA-262.pdf |title=ECMAScript Language Specification |page=43 |url-status=dead |archive-url=https://web.archive.org/web/20150412040502/http://www.ecma-international.org/publications/files/ECMA-ST/Ecma-262.pdf |archive-date=2015-04-12 |access-date=2011-03-12 }}</ref> are sometimes called ''falsy'' (of which the [[Complement (set theory)|complement]] is ''truthy'') to distinguish between strictly [[Type safety|type-checked]] and [[Type conversion|coerced]] Booleans (see also: [[JavaScript syntax#Type conversion]]).<ref>{{cite web |url=http://javascript.crockford.com/style2.html |title=The Elements of JavaScript Style |publisher=Douglas Crockford |access-date=5 March 2011 |url-status=live |archive-url=https://web.archive.org/web/20110317074944/http://javascript.crockford.com/style2.html |archive-date=17 March 2011 }}</ref> As opposed to Python, empty containers (Arrays, Maps, Sets) are considered truthy. Languages such as [[PHP]] also use this approach.