std::basic_string_view<CharT,Traits>::data
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std::basic_string_view
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(C++23)
basic_string_view::data
Constants
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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.
[edit] Parameters
(none)
[edit] Return value
A pointer to the underlying character array.
[edit] Complexity
Constant.
[edit] Notes
Unlike std::basic_string::data() and string literals, std::basic_string_view::data() returns a pointer to a buffer that is not necessarily null-terminated, for example a substring view (e.g. from remove_suffix). Therefore, it is typically a mistake to pass data() to a routine that takes just a const CharT* and expects a null-terminated string.
[edit] Example
Run this code
#include <cstring> #include <cwchar> #include <iostream> #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