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std::basic_string<CharT,Traits,Allocator>::data - cppreference.com

From cppreference.com

const CharT* data() const;
(1) (noexcept since C++11)
(constexpr since C++20)
(2) (since C++17)
(constexpr since C++20)

Returns a pointer to the underlying array serving as character storage. The pointer is such that the range

[data(), data() + size())

(until C++11)

[data(), data() + size()]

(since C++11)

is valid and the values in it correspond to the values stored in the string.

The returned array is not required to be null-terminated.

If empty() returns true, the pointer is a non-null pointer that should not be dereferenced.

(until C++11)

The returned array is null-terminated, that is, data() and c_str() perform the same function.

If empty() returns true, the pointer points to a single null character.

(since C++11)

The pointer obtained from data() may be invalidated by:

  • Passing a non-const reference to the string to any standard library function, or
  • Calling non-const member functions on the string, excluding operator[](), at(), front(), back(), begin(), end(), rbegin(), rend().

1) Modifying the character array accessed through the const overload of data has undefined behavior.

2) Modifying the past-the-end null terminator stored at data() + size() to any value other than CharT() has undefined behavior.

Parameters

(none)

Return value

A pointer to the underlying character storage.

data()[i] == operator[](i) for every i in [0, size()).

(until C++11)

data() + i == std::addressof(operator[](i)) for every i in [0, size()].

(since C++11)

Complexity

Constant.

Example

#include <algorithm>
#include <cassert>
#include <cstring>
#include <string>

int main()
{
    std::string const s("Emplary");
    assert(s.size() == std::strlen(s.data()));
    assert(std::equal(s.begin(), s.end(), s.data()));
    assert(std::equal(s.data(), s.data() + s.size(), s.begin()));
    assert('\0' == *(s.data() + s.size()));
}

See also

accesses the first character
(public member function) [edit]
accesses the last character
(public member function) [edit]
returns a non-modifiable standard C character array version of the string
(public member function) [edit]
returns a pointer to the first character of a view
(public member function of std::basic_string_view<CharT,Traits>) [edit]