Editing Value (computer science) (section)

=== {{Anchor|lrvalue}}Assignment: l-values and r-values ===
Some languages use the idea of '''l-values''' and '''r-values''', deriving from the typical mode of evaluation on the left and right-hand side of an assignment statement. An l-value refers to an object that persists beyond a single expression. An r-value is a temporary value that does not persist beyond the expression that uses it.<ref>{{cite web|title=Lvalues and Rvalues (Visual C++)|url=https://msdn.microsoft.com/en-us/library/f90831hc.aspx|website=Microsoft Developer Network|access-date=3 September 2016}}</ref>

The notion of l-values and r-values was introduced by [[Combined Programming Language]] (CPL). The notions in an expression of r-value, l-value, and r-value/l-value are analogous to the [[Parameter (computer programming)|parameter]] modes of input parameter (has a value), [[output parameter]] (can be assigned), and input/output parameter (has a value and can be assigned), though the technical details differ between contexts and languages.