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

std::basic_string_view<CharT,Traits>::data: std::basic_string_view<CharT,Traits>::data

NAME

std::basic_string_view<CharT,Traits>::data - std::basic_string_view<CharT,Traits>::data

Synopsis

constexpr const_pointer data() const noexcept; (since C++17)

Returns a pointer to the underlying character array. The pointer is such that the range [data(); data() + size()) is valid and the values in it correspond to the values of the view.

Parameters

(none)

Return value

A pointer to the underlying character array.

Complexity

Constant.

Notes

Unlike std::basic_string::data() and string literals, data() may return a pointer to a buffer that is not null-terminated. Therefore it is typically a mistake to pass data() to a routine that takes just a const CharT* and expects a null-terminated string.

Example

// Run this code

  #include <iostream>
  #include <cstring>
  #include <cwchar>
  #include <string>
  #include <string_view>
  int main()
  {
      std::wstring_view wcstr_v = L"xyzzy";
      std::cout << std::wcslen(wcstr_v.data()) << '\n';
      // OK: the underlying character array is null-terminated

      char array[3] = {'B', 'a', 'r'};
      std::string_view array_v(array, sizeof array);
      // std::cout << std::strlen(array_v.data()) << '\n';
      // error: the underlying character array is not null-terminated

      std::string str(array_v.data(), array_v.size()); // OK
      std::cout << std::strlen(str.data()) << '\n';
      // OK: the underlying character array of a std::string is always null-terminated
  }

Output:

  5
  3