std::string data() method

since C++20

// (1) Const version
constexpr const CharT* data() const noexcept;

// (2) Non const version
constexpr CharT* data() noexcept;

since C++17

// (1) Const version
const CharT* data() const noexcept;

since C++11

// (1) Const version
const CharT* data() const noexcept;

until C++11

// (1) Const version only
const CharT* data() const;

since C++11

Returns a pointer to the underlying array serving as character storage.

The pointer is such that the range: ** [ data(); data() + size() ]** is valid and the values in it correspond to the values stored in the string.

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

important

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

until C++11

Returns a pointer to the underlying array serving as character storage.

The pointer is such that the range: ** [ data(); data() + size() )** 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.

caution

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

Invalidation

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().

Undefined Behavior

• (1) Modifying the character array accessed through the const overload of data results in undefined behavior.
• (2) Modifying the past-the-end null terminator stored at data() + size() to any value other than CharT() is undefined behavior.

Parameters

(none)

Return value

A pointer to the underlying character storage.

since C++11

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() ].

Complexity

Constant - O(1).

Notes

c_str() and data() perform the same function. (since C++11)

Example

Main.cpp

#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()));
}