std::basic_string<CharT,Traits,Allocator>::data (3) - Linux Manuals

std::basic_string<CharT,Traits,Allocator>::data: std::basic_string<CharT,Traits,Allocator>::data


std::basic_string<CharT,Traits,Allocator>::data - std::basic_string<CharT,Traits,Allocator>::data


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

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. (until C++11)
If empty() returns true, the pointer is a non-null pointer that should not be dereferenced.
The returned array is null-terminated, that is, data() and c_str() perform the same function. (since C++11)
If empty() returns true, the pointer points to a single null character.

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.



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)




// Run this code

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

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

See also

front accesses the first character
        (public member function)

back accesses the last character
        (public member function)
        returns a non-modifiable standard C character array version of the string
c_str (public member function)