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

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< cpp‎ | string‎ | basic string

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

Run this code

    #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

front (DR*) | accesses the first character (public member function)
back (DR*) | accesses the last character (public member function)
c_str | returns a non-modifiable standard C character array version of the string (public member function)
data (C++17) | returns a pointer to the first character of a view (public member function of `std::basic_string_view<CharT,Traits>`)

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