< cpp‎ | container‎ | vector
T* data();
(1) (noexcept since C++11)
(constexpr since C++20)
const T* data() const;
(2) (noexcept since C++11)
(constexpr 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).


[edit] Parameters


[edit] Return value

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

[edit] Complexity


[edit] Notes

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

[edit] Example

#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 over &container[0]
    pointer_func(, container.size());
    // std::span (C++20) is a safer alternative to separated pointer/size.
    span_func({, container.size()});


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

[edit] See also

access the first element
(public member function) [edit]
access the last element
(public member function) [edit]
returns the number of elements
(public member function) [edit]
a non-owning view over a contiguous sequence of objects
(class template) [edit]
obtains the pointer to the underlying array
(function template) [edit]