std::vector data() method

since C++20

// Non-const version
constexpr T*        data() noexcept;

// Const version
constexpr T const*  data() const noexcept;

since C++11

// Non-const version
T*        data() noexcept;

// Const version
T const*  data() const noexcept;

until C++11

// Non-const version
T*        data();

// Const version
T const*  data() const;

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.

Undefined Behaviour

If the container is empty, dereferencing the pointer returned by data() is undefined behavior

.

Parameters

(none)

Return value

Pointer to the underlying element storage.
For a non-empty container c, the returned pointer compares equal to the address of the first element - c.data() == &c[0];

Complexity

Constant - O(1)**.

Notes

If the container is empty, data() may or may not return a null pointer.

Example

Main.cpp

#include <array>
#include <iostream>
 
int main()
{
    std::vector<char> letters {'a', 'b', 'c', 'd', 'e', 'f'};
 
    if (!letters.empty()) {
        std::cout << "The last character is '" << letters.back() << "'.\n";
    }  
}

Output

The last character is 'f'.