< cpp‎ | experimental‎ | ranges
Technical specifications
Filesystem library (filesystem TS)
Library fundamentals (library fundamentals TS)
Library fundamentals 2 (library fundamentals 2 TS)
Extensions for parallelism (parallelism TS)
Extensions for parallelism 2 (parallelism TS v2)
Extensions for concurrency (concurrency TS)
Concepts (concepts TS)
Ranges (ranges TS)
Special mathematical functions (special math TR)
Iterators library
Iterator concepts
Indirect callable concepts
Common algorithm requirements
Concept utilities
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Stream iterators
namespace {

    constexpr /* unspecified */ prev = /* unspecified */;

(ranges TS)
(customization point object)
Call signature
template< Iterator I >
constexpr I prev(I i);
template< Iterator I >
constexpr I prev(I i, ranges::difference_type_t<I> n);
template< Iterator I >
constexpr I prev(I i, ranges::difference_type_t<I> n, I bound);

Decrements the iterator i n times, or until bound is reached, whichever comes first, and returns the decremented iterator.

1) Equivalent to --i; return i;.
2) Equivalent to ranges::advance(i, -n); return i;.
3) Equivalent to ranges::advance(i, -n, bound); return i;.

Customization point objects

The name ranges::prev denotes a customization point object, which is a function object of a literal Semiregular class type (denoted, for exposition purposes, as PrevT). All instances of PrevT are equal. Thus, ranges::prev can be copied freely and its copies can be used interchangeably.

Given a set of types Args..., if std::declval<Args>()... meet the requirements for arguments to ranges::prev above, PrevT will satisfy ranges::Invocable<const PrevT, Args...>. Otherwise, no function call operator of PrevT participates in overload resolution.

In every translation unit in which ranges::prev is defined, it refers to the same instance of the customization point object. (This means that it can be used freely in things like inline functions and function templates without violating the one-definition rule.)

Return value

The decremented iterator.


See also

decrement an iterator
(function template)
advances an iterator by given distance
(function template)
increment an iterator
(function template)
returns the distance between an iterator and a sentinel, or between the beginning and the end of a range
(function template)