[#absl-Span]
= xref:absl.adoc[absl]::Span
:relfileprefix: ../
:mrdocs:

A non‐owning view over a contiguous sequence of objects.

== Synopsis

Declared in `<absl/types/span.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<typename T>
class Span;
----

== Description

A `Span` provides a bounds‐checked, `std::vector`‐like interface over an array whose storage is owned elsewhere. It can be constructed from a pointer and length, a C array, or any contiguous container, and it must not outlive the data it refers to.

== Type Aliases

[cols="1,4"]
|===
| Name| Description
| xref:absl/Span/absl_internal_is_view.adoc[`absl_internal_is_view`] 
| Tag marking `Span` as a view type.
| xref:absl/Span/const_iterator.adoc[`const_iterator`] 
| A random‐access iterator over const elements.
| xref:absl/Span/const_pointer.adoc[`const_pointer`] 
| A pointer to a const element.
| xref:absl/Span/const_reference.adoc[`const_reference`] 
| A reference to a const element.
| xref:absl/Span/const_reverse_iterator.adoc[`const_reverse_iterator`] 
| A reverse iterator over const elements.
| xref:absl/Span/difference_type.adoc[`difference_type`] 
| A signed type used for iterator differences.
| xref:absl/Span/element_type.adoc[`element_type`] 
| The element type, including any cv‐qualification.
| xref:absl/Span/iterator.adoc[`iterator`] 
| A random‐access iterator over the elements.
| xref:absl/Span/pointer.adoc[`pointer`] 
| A pointer to an element.
| xref:absl/Span/reference.adoc[`reference`] 
| A reference to an element.
| xref:absl/Span/reverse_iterator.adoc[`reverse_iterator`] 
| A reverse iterator over the elements.
| xref:absl/Span/size_type.adoc[`size_type`] 
| An unsigned type used for sizes and indices.
| xref:absl/Span/value_type.adoc[`value_type`] 
| The element type with cv‐qualifiers removed.
|===


== Member Functions

[cols="1,4"]
|===
| Name| Description
| xref:absl/Span/2constructor-0a1.adoc[`Span`]         [.small]#[constructor]#
| Constructors
| xref:absl/Span/at.adoc[`at`] 
| Returns a reference to the `i`th element, with bounds checking.
| xref:absl/Span/back.adoc[`back`] 
| Returns a reference to the last element; the span must not be empty.
| xref:absl/Span/begin.adoc[`begin`] 
| Returns an iterator to the first element.
| xref:absl/Span/cbegin.adoc[`cbegin`] 
| Returns a const iterator to the first element.
| xref:absl/Span/cend.adoc[`cend`] 
| Returns a const iterator just past the last element.
| xref:absl/Span/crbegin.adoc[`crbegin`] 
| Returns a const reverse iterator to the last element.
| xref:absl/Span/crend.adoc[`crend`] 
| Returns a const reverse iterator just before the first element.
| xref:absl/Span/data.adoc[`data`] 
| Returns a pointer to the span's underlying array of data.
| xref:absl/Span/empty.adoc[`empty`] 
| Reports whether this span is empty.
| xref:absl/Span/end.adoc[`end`] 
| Returns an iterator just past the last element.
| xref:absl/Span/first.adoc[`first`] 
| Returns a span containing the first `len` elements.
| xref:absl/Span/front.adoc[`front`] 
| Returns a reference to the first element; the span must not be empty.
| xref:absl/Span/last.adoc[`last`] 
| Returns a span containing the last `len` elements.
| xref:absl/Span/length.adoc[`length`] 
| Returns the length (size) of this span.
| xref:absl/Span/operator_subs.adoc[`operator[]`] 
| Returns a reference to the `i`th element of this span.
| xref:absl/Span/rbegin.adoc[`rbegin`] 
| Returns a reverse iterator to the last element.
| xref:absl/Span/remove_prefix.adoc[`remove_prefix`] 
| Removes the first `n` elements from the span.
| xref:absl/Span/remove_suffix.adoc[`remove_suffix`] 
| Removes the last `n` elements from the span.
| xref:absl/Span/rend.adoc[`rend`] 
| Returns a reverse iterator just before the first element.
| xref:absl/Span/size.adoc[`size`] 
| Returns the number of elements in this span.
| xref:absl/Span/subspan.adoc[`subspan`] 
| Returns a subspan starting at `pos` and spanning `len` elements.
|===


== Static Data Members

[cols="1,4"]
|===
| Name| Description
| xref:absl/Span/npos.adoc[`npos`] 
| Sentinel size value meaning "until the end of the span".
|===


== Friends

[cols="1,4"]
|===
| Name| Description
| `xref:absl/AbslHashValue-03.adoc[absl::AbslHashValue]`
| Hashes the span's elements for use with `absl::Hash`.
|===

== Non-Member Functions

[cols="1,4"]
|===
| Name| Description
| xref:absl/MakeConstSpan-05.adoc[`MakeConstSpan`]
| Constructs a `Span<const T>` from a pointer and a size.
| xref:absl/MakeConstSpan-06.adoc[`MakeConstSpan`]
| Constructs a `Span<const T>` from a C array.
| xref:absl/MakeConstSpan-07.adoc[`MakeConstSpan`]
| Constructs a `Span<const T>` from a `[begin, end)]` pointer pair.
| xref:absl/MakeSpan-0e2.adoc[`MakeSpan`]
| Constructs a mutable `Span<T>` from a C array.
| xref:absl/MakeSpan-0e4.adoc[`MakeSpan`]
| Constructs a mutable `Span<T>` from a pointer and a size.
| xref:absl/MakeSpan-0f.adoc[`MakeSpan`]
| Constructs a mutable `Span<T>` from a `[begin, end)]` pointer pair.
| xref:absl/operator_not_eq-0624.adoc[`operator!=`]
| Compares two spans for inequality.
| xref:absl/operator_not_eq-077.adoc[`operator!=`]
| Compares a span to a container for inequality.
| xref:absl/operator_not_eq-0a.adoc[`operator!=`]
| Compares two spans for inequality.
| xref:absl/operator_not_eq-0e4.adoc[`operator!=`]
| Compares two spans for inequality.
| xref:absl/operator_lt-04c.adoc[`operator<`]
| Compares two spans lexicographically.
| xref:absl/operator_lt-06d.adoc[`operator<`]
| Compares two spans lexicographically.
| xref:absl/operator_lt-08.adoc[`operator<`]
| Compares two spans lexicographically.
| xref:absl/operator_lt-0ed.adoc[`operator<`]
| Compares a span and a container lexicographically.
| xref:absl/operator_le-003.adoc[`operator<=`]
| Compares two spans lexicographically.
| xref:absl/operator_le-0bf.adoc[`operator<=`]
| Compares two spans lexicographically.
| xref:absl/operator_le-0d.adoc[`operator<=`]
| Compares two spans lexicographically.
| xref:absl/operator_le-0e.adoc[`operator<=`]
| Compares a span and a container lexicographically.
| xref:absl/operator_eq-02b.adoc[`operator==`]
| Compares two spans for element‐wise equality.
| xref:absl/operator_eq-084.adoc[`operator==`]
| Compares two spans for element‐wise equality.
| xref:absl/operator_eq-0c1.adoc[`operator==`]
| Compares a span to a container for element‐wise equality.
| xref:absl/operator_eq-0d6.adoc[`operator==`]
| Compares two spans for element‐wise equality.
| xref:absl/operator_gt-085.adoc[`operator>`]
| Compares two spans lexicographically.
| xref:absl/operator_gt-08f.adoc[`operator>`]
| Compares two spans lexicographically.
| xref:absl/operator_gt-091.adoc[`operator>`]
| Compares two spans lexicographically.
| xref:absl/operator_gt-0c7.adoc[`operator>`]
| Compares a span and a container lexicographically.
| xref:absl/operator_ge-03e0.adoc[`operator>=`]
| Compares two spans lexicographically.
| xref:absl/operator_ge-03ec.adoc[`operator>=`]
| Compares two spans lexicographically.
| xref:absl/operator_ge-04e.adoc[`operator>=`]
| Compares two spans lexicographically.
| xref:absl/operator_ge-06.adoc[`operator>=`]
| Compares a span and a container lexicographically.
|===


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