std::data

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Compiler support
Freestanding and hosted
Language
Standard library
Standard library headers
Named requirements
Feature test macros(C++20)
Language support library
Concepts library(C++20)
Diagnostics library
Memory management library
Metaprogramming library(C++11)
General utilities library
Containers library
Iterators library
Ranges library(C++20)
Algorithms library
Strings library
Text processing library
Numerics library
Date and time library
Input/output library
Filesystem library(C++17)
Concurrency support library(C++11)
Execution control library(C++26)
Technical specifications
Symbols index
External libraries

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Iterator library

Iterator concepts

indirectly_readable (C++20)
indirectly_writable (C++20)
weakly_incrementable (C++20)
incrementable (C++20)
is-integer-like is-signed-integer-like (C++20)(C++20)

sentinel_for (C++20)
sized_sentinel_for (C++20)
input_iterator (C++20)
output_iterator (C++20)
input_or_output_iterator (C++20)

forward_iterator (C++20)
bidirectional_iterator (C++20)
random_access_iterator (C++20)
contiguous_iterator (C++20)

Iterator primitives

input_iterator_tagoutput_iterator_tagforward_iterator_tagbidirectional_iterator_tagrandom_access_iterator_tagcontiguous_iterator_tag

(C++20)

iter_value_titer_difference_titer_reference_titer_const_reference_titer_rvalue_reference_titer_common_reference_t

(C++20)(C++20)(C++20)(C++23)(C++20)(C++20)

iterator (deprecated in C++17)
iterator_traits
incrementable_traits (C++20)
indirectly_readable_traits (C++20)

Algorithm concepts and utilities

Indirect callable concepts

indirectly_unary_invocableindirectly_regular_unary_invocable

(C++20)(C++20)

indirect_unary_predicate (C++20)
indirect_binary_predicate (C++20)

indirect_equivalence_relation (C++20)
indirect_strict_weak_order (C++20)

Common algorithm requirements

indirectly_movable (C++20)
indirectly_movable_storable (C++20)
indirectly_copyable (C++20)

indirectly_copyable_storable (C++20)
indirectly_swappable (C++20)
indirectly_comparable (C++20)

permutable (C++20)
mergeable (C++20)
sortable (C++20)

(C++20)

(C++20)

(C++26)

reverse_iterator
make_reverse_iterator (C++14)
move_iterator (C++11)
make_move_iterator (C++11)
default_sentinel_tdefault_sentinel (C++20)(C++20)
unreachable_sentinel_tunreachable_sentinel (C++20)(C++20)

front_insert_iterator
back_insert_iterator
inserter
insert_iterator
front_inserter
back_inserter
move_sentinel (C++20)

common_iterator (C++20)
counted_iterator (C++20)
basic_const_iterator (C++23)
const_iterator (C++23)
const_sentinel (C++23)
make_const_iterator (C++23)
make_const_sentinel (C++23)

Stream iterators

istream_iterator
ostream_iterator

istreambuf_iterator
ostreambuf_iterator

Iterator customization points
ranges::iter_move (C++20)
ranges::iter_swap (C++20)

Iterator operations

advance
distance
prev (C++11)
next (C++11)

ranges::advance (C++20)
ranges::distance (C++20)
ranges::prev (C++20)
ranges::next (C++20)

Range access

begincbegin (C++11)(C++14)
rbegincrbegin (C++14)(C++14)

endcend (C++11)(C++14)
rendcrend (C++14)(C++14)

sizessize (C++17)(C++20)
empty (C++17)
data (C++17)

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Defined in header`<array>`
Defined in header`<deque>`
Defined in header`<flat_map>`
Defined in header`<flat_set>`
Defined in header`<forward_list>`
Defined in header`<inplace_vector>`
Defined in header`<iterator>`
Defined in header`<list>`
Defined in header`<map>`
Defined in header`<regex>`
Defined in header`<set>`
Defined in header`<span>`
Defined in header`<string>`
Defined in header`<string_view>`
Defined in header`<unordered_map>`
Defined in header`<unordered_set>`
Defined in header`<vector>`
template<class C> constexprauto data( C& c)-> decltype(c.data());	(1)	(since C++17)
template<class C> constexprauto data(const C& c)-> decltype(c.data());	(2)	(since C++17)
template<class T,std::size_t N> constexpr T* data( T(&array)[N])noexcept;	(3)	(since C++17)
template<class E> constexprconst E* data(std::initializer_list<E> il)noexcept;	(4)	(since C++17)

Returns a pointer to the block of memory containing the elements of the range.

1,2) Returnsc.data().

3) Returnsarray.

4) Returnsil.begin().

[edit]Parameters

c	-	a container or view with adata() member function
array	-	an array of arbitrary type
il	-	anstd::initializer_list

[edit]Return value

1,2)c.data()

3)array

4)il.begin()

[edit]Exceptions

1) May throw implementation-defined exceptions.

[edit]Notes

The overload forstd::initializer_list is necessary because it does not have a member functiondata.

Feature-test macro	Value	Std	Feature
`__cpp_lib_nonmember_container_access`	`201411L`	(C++17)	std::size(),`std::data()`, andstd::empty()

[edit]Possible implementation

First version
template<class C>constexprauto data(C& c)-> decltype(c.data()){return c.data();}
Second version
template<class C>constexprauto data(const C& c)-> decltype(c.data()){return c.data();}
Third version
template<class T,std::size_t N>constexpr T* data(T(&array)[N])noexcept{return array;}
Fourth version
template<class E>constexprconst E* data(std::initializer_list<E> il)noexcept{return il.begin();}

[edit]Example

Run this code

#include <cstring>#include <iostream>#include <string> int main(){std::string s{"Hello world!\n"}; char a[20];// storage for a C-style stringstd::strcpy(a, std::data(s));//  [s.data(), s.data() + s.size()] is guaranteed to be an NTBS since C++11 std::cout<< a;}

Output:

Hello world!

[edit]See also

ranges::data (C++20)	obtains a pointer to the beginning of a contiguous range (customization point object)[edit]
ranges::cdata (C++20)	obtains a pointer to the beginning of a read-only contiguous range (customization point object)[edit]