std::vector<T,Allocator>::data

 

C++

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)

Metaprogramming library (C++11)

Diagnostics library

General utilities library

Strings library

Containers library

Iterators library

Ranges library (C++20)

Algorithms library

Numerics library

Localizations library

Input/output library

Filesystem library (C++17)

Regular expressions library (C++11)

Concurrency support library (C++11)

Technical specifications

Symbols index

External libraries

 

Containers library

Sequence

array (C++11)

vector

vector<bool>

deque

forward_list (C++11)

list

Associative

set

multiset

map

multimap

Unordered associative

unordered_set (C++11)

unordered_multiset (C++11)

unordered_map (C++11)

unordered_multimap (C++11)

Adaptors

stack

queue

priority_queue

flat_set (C++23)

flat_multiset (C++23)

flat_map (C++23)

flat_multimap (C++23)

Views

span (C++20)

mdspan (C++23)

Iterator invalidation

Member function table

Non-member function table

 

std::vector

Member types

Member functions

vector::vector

vector::~vector

vector::operator=

vector::assign

vector::assign_range (C++23)

vector::get_allocator

Element access

vector::at

vector::operator[]

vector::front

vector::back

vector::data

Iterators

vector::beginvector::cbegin (C++11)

vector::endvector::cend (C++11)

vector::rbeginvector::crbegin (C++11)

vector::rendvector::crend (C++11)

Capacity

vector::empty

vector::size

vector::max_size

vector::reserve

vector::capacity

vector::shrink_to_fit (DR*)

Modifiers

vector::clear

vector::insert

vector::emplace (C++11)

vector::insert_range (C++23)

vector::erase

vector::push_back

vector::emplace_back (C++11)

vector::append_range (C++23)

vector::pop_back

vector::resize

vector::swap

Non-member functions

std::swap

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

operator==operator!=operator<operator>operator<=operator>=operator<=> (until C++20)(until C++20)(until C++20)(until C++20)(until C++20)(C++20)

Deduction guides(C++17)

 

	(1)
T* data();			(until C++11)
T* data() noexcept;			(since C++11) (until C++20)
constexpr T* data() noexcept;			(since C++20)
		(2)
const T* data() const;				(until C++11)
const T* data() const noexcept;				(since C++11) (until C++20)
constexpr const T* data() const noexcept;				(since C++20)

Returns pointer to the underlying array serving as element storage. The pointer is such that range [data(), data() + size()) is always a valid range, even if the container is empty (data() is not dereferenceable in that case).

Parameters

(none)

Return value

Pointer to the underlying element storage. For non-empty containers, the returned pointer compares equal to the address of the first element.

Complexity

Constant.

Notes

If size() is ​0​, data() may or may not return a null pointer.

Example

Run this code

#include <cstddef>
#include <iostream>
#include <span>
#include <vector>
 
void pointer_func(const int* p, std::size_t size)
{
    std::cout << "data = ";
    for (std::size_t i = 0; i < size; ++i)
        std::cout << p[i] << ' ';
    std::cout << '\n';
}
 
void span_func(std::span<const int> data) // since C++20
{
    std::cout << "data = ";
    for (const int e : data)
        std::cout << e << ' ';
    std::cout << '\n';
}
 
int main()
{
    std::vector<int> container{1, 2, 3, 4};
 
    // Prefer container.data() over &container[0]
    pointer_func(container.data(), container.size());
 
    // std::span (C++20) is a safer alternative to separated pointer/size.
    span_func({container.data(), container.size()});
}

Output:

data = 1 2 3 4 
data = 1 2 3 4

Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

DR	Applied to	Behavior as published	Correct behavior
LWG 464	C++98	vector did not have this member function	added
LWG 1312	C++98	the return type were pointer and const_pointer	changed to T* and const T* respectively

See also

front	access the first element (public member function)
back	access the last element (public member function)
size	returns the number of elements (public member function)
span (C++20)	a non-owning view over a contiguous sequence of objects (class template)
data (C++17)	obtains the pointer to the underlying array (function template)