[#BloombergLP-bslstl-BidirectionalIterator]
= xref:BloombergLP.adoc[BloombergLP]::xref:BloombergLP/bslstl.adoc[bslstl]::BidirectionalIterator
:relfileprefix: ../../
:mrdocs:

Adaptor that produces a standard bidirectional iterator from a core type.

== Synopsis

Declared in `<bslstl_bidirectionaliterator.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<
    class T,
    class ITER_IMP,
    class TAG_TYPE = std::bidirectional_iterator_tag>
class BidirectionalIterator
    : public xref:BloombergLP/bslstl/ForwardIterator.adoc[ForwardIterator<T, ITER_IMP, TAG_TYPE>]
----

== Description

Given an `ITER_IMP` type that implements a minimal subset of an iterator interface, this template generates a complete iterator that meets all of the requirements of a "bidirectional iterator" in the C++ standard. If `T` is `const`‐qualified, then the resulting type is a constant iterator. `T` shall not be a function, reference type or void. `ITER_IMP` must provide public operations so that, for objects `i` and `j` of type `ITER_IMP`, the following operations are supported: ` ITER_IMP i; default construction ITER_IMP j(i); copy construction i = j assignment ++i increment to next element ‐‐i decrement to previous element i == j // convertible to bool equality comparison *i // reference convertible to T& element access (dereference) `

== Base Classes

[cols="1,4"]
|===
| Name| Description
| `xref:BloombergLP/bslstl/ForwardIterator.adoc[ForwardIterator<T, ITER_IMP, TAG_TYPE>]`
| STL‐compliant forward iterator adapted from a minimal implementation.
|===

== Type Aliases

[cols="1,4"]
|===
| Name| Description
| xref:BloombergLP/bslstl/BidirectionalIterator/difference_type.adoc[`difference_type`] 
| Type of the distance between two iterators.
| xref:BloombergLP/bslstl/BidirectionalIterator/iterator_category.adoc[`iterator_category`] 
| Standard iterator category tag for bidirectional iterators.
| xref:BloombergLP/bslstl/BidirectionalIterator/pointer.adoc[`pointer`] 
| Pointer type for the iterator's element type.
| xref:BloombergLP/bslstl/BidirectionalIterator/reference.adoc[`reference`] 
| Reference type for the iterator's element type.
| xref:BloombergLP/bslstl/BidirectionalIterator/value_type.adoc[`value_type`] 
| Type of the value obtained when dereferencing the iterator.
|===


== Member Functions

[cols="1,4"]
|===
| Name| Description
| xref:BloombergLP/bslstl/BidirectionalIterator/2constructor-09.adoc[`BidirectionalIterator`]         [.small]#[constructor]#
| Constructors
| xref:BloombergLP/bslstl/BidirectionalIterator/operator_assign-05.adoc[`operator=`] 
| Assignment operators
| xref:BloombergLP/bslstl/ForwardIterator/imp-0e.adoc[`imp`] 
| `imp` overloads
| xref:BloombergLP/bslstl/ForwardIterator/operator_star.adoc[`operator*`] 
| Return a reference to the current element.
| xref:BloombergLP/bslstl/BidirectionalIterator/operator_inc.adoc[`operator++`] 
| Advance this iterator to the next element.
| xref:BloombergLP/bslstl/BidirectionalIterator/operator_dec.adoc[`operator‐‐`] 
| Regress this iterator to the previous element.
| xref:BloombergLP/bslstl/ForwardIterator/operator_ptr.adoc[`operator‐>`] 
| Return a pointer to the current element.
|===


== Non-Member Functions

[cols="1,4"]
|===
| Name| Description
| xref:BloombergLP/bslstl/operator_not_eq-0bc.adoc[`operator!=`]
| Return `true` if `lhs` and `rhs` do not have the same value.
| xref:BloombergLP/bslstl/operator_not_eq-0d.adoc[`operator!=`]
| Return whether two bidirectional iterators refer to different positions.
| xref:BloombergLP/bslstl/operator_inc-008.adoc[`operator++`]
| Advance `iter` to the next element and return its previous value.
| xref:BloombergLP/bslstl/operator_inc-07.adoc[`operator++`]
| Post‐increment the specified iterator and return its previous value.
| xref:BloombergLP/bslstl/operator_dec-08.adoc[`operator‐‐`]
| Post‐decrement the specified iterator and return its previous value.
| xref:BloombergLP/bslstl/operator_eq-066.adoc[`operator==`]
| Return `true` if `lhs` and `rhs` have the same value.
| xref:BloombergLP/bslstl/operator_eq-08.adoc[`operator==`]
| Return whether two bidirectional iterators refer to the same position.
|===

== Derived Classes

[cols="1,4"]
|===
| Name| Description
| xref:BloombergLP/bslstl/RandomAccessIterator.adoc[`RandomAccessIterator`] 
| STL‐compliant random‐access iterator adapted from a minimal implementation.
|===


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