[alg.clamp]

# 26 Algorithms library [[algorithms]](./#algorithms)

## 26.8 Sorting and related operations [[alg.sorting]](alg.sorting#alg.clamp)

### 26.8.10 Bounded value [alg.clamp]

[🔗](#lib:clamp)

`template<class T>
  constexpr const T& clamp(const T& v, const T& lo, const T& hi);
template<class T, class Compare>
  constexpr const T& clamp(const T& v, const T& lo, const T& hi, Compare comp);
template<class T, class Proj = identity,
         [indirect_strict_weak_order](indirectcallable.indirectinvocable#concept:indirect_strict_weak_order "24.3.6.3 Indirect callables [indirectcallable.indirectinvocable]")<projected<const T*, Proj>> Comp = ranges::less>
  constexpr const T&
    ranges::clamp(const T& v, const T& lo, const T& hi, Comp comp = {}, Proj proj = {});
`

[1](#1)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/algorithms.tex#L11714)

Let comp be less{} for the overloads with no parameter comp,
and let proj be identity{} for the overloads with no parameter proj[.](#1.sentence-1)

[2](#2)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/algorithms.tex#L11720)

*Preconditions*: bool(invoke(comp, invoke(proj, hi), invoke(proj, lo))) is false[.](#2.sentence-1)

For the first form, type T meets the [*Cpp17LessThanComparable*](utility.arg.requirements#:Cpp17LessThanComparable "16.4.4.2 Template argument requirements [utility.arg.requirements]") requirements (Table [29](utility.arg.requirements#tab:cpp17.lessthancomparable "Table 29: Cpp17LessThanComparable requirements"))[.](#2.sentence-2)

[3](#3)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/algorithms.tex#L11727)

*Returns*: lo if bool(invoke(comp, invoke(proj, v), invoke(proj, lo))) is true,hi if bool(​invoke(comp, invoke(proj, hi), invoke(proj, v))) is true,
otherwise v[.](#3.sentence-1)

[4](#4)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/algorithms.tex#L11733)

[*Note [1](#note-1)*:

If NaN is avoided, T can be a floating-point type[.](#4.sentence-1)

— *end note*]

[5](#5)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/algorithms.tex#L11738)

*Complexity*: At most two comparisons and three applications of the projection[.](#5.sentence-1)