inrange

Inrange is a term used in programming and mathematics to denote that a numeric value lies within a defined interval. It typically refers to a predicate or function that evaluates whether a value satisfies specified boundary conditions.

Variants of inrange describe different boundary inclusions. A common form is inclusive, where the lower and upper bounds are included: lower <= x <= upper. Some contexts use exclusive ranges, where the bounds are not included: lower < x < upper. Half-open or half-closed intervals (such as [lower, upper)) are also common in certain languages and libraries.

Typical uses of inrange include input validation, constraint checking, iterative pruning in algorithms, and ensuring values stay within safe or expected limits. It is also used in user interfaces to validate slider inputs or to enforce domain restrictions in computations. When implementing inrange, considerations include whether the bounds are inclusive or exclusive, performance implications of the language’s comparison semantics, and how special values like NaN or infinities should be treated.

Common approaches are language-agnostic. A simple inclusive version in pseudocode might be:

function inrange(x, lower, upper) return (lower <= x) and (x <= upper)

A variant for exclusive bounds would be:

function inrange_exclusive(x, lower, upper) return (lower < x) and (x < upper)

In some libraries, the concept is exposed as inRange, InRange, or a similar predicate or helper, with syntax adapted to the host language. See also range, interval, and membership tests.