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std::wstrin...:from_bytes(3) C++ Standard Libary std::wstrin...:from_bytes(3) NAME std::wstring_convert::from_bytes - std::wstring_convert::from_bytes Synopsis Defined in header <locale> wide_string from_bytes( char byte ); (1) wide_string from_bytes( const char* ptr ); (2) wide_string from_bytes( const byte_string& str ); (3) wide_string from_bytes( const char* first, const char* last); (4) Performs multibyte to wide conversion, using the codecvt facet sup- plied at construction. 1) Converts byte as if it was a string of length 1 to wide_string 2) Converts the null-terminated multibyte character sequence begin- ning at the character pointed to by ptr to wide_string 3) Converts the narrow string str to wide_string. 4) Converts the narrow multibyte character sequence [first, last) to wide_string In all cases, the conversion begins in initial shift state, unless non-initial starting state was provided to this wstring_convert constructor. The number of characters converted and the final value of the conversion state are remembered and can be accessed with state() and converted() Return value A wide_string object containing the results of multibyte to wide conversion. If the conversion failed and there was a user-supplied wide-error string provided to the constructor of this wstring_convert, returns that wide-error string. Exceptions If this wstring_convert object was constructed without a user-sup- plied wide-error string, throws std::range_error on conversion failure. Example // Run this code #include <iostream> #include <string> #include <locale> #include <codecvt> int main() { std::string utf8 = u8"z\u00df\u6c34\U0001d10b"; // or u8"z" // or "\x7a\xc3\x9f\xe6\xb0\xb4\xf0\x9d\x84\x8b"; // the UTF-8 / UTF-16 standard conversion facet std::u16string utf16 = std::wstring_con- vert<std::codecvt_utf8_utf16<char16_t>, char16_t>{}.from_bytes(utf8.data()); std::cout << "UTF16 conversion produced " << utf16.size() << " code units:\n"; for (char16_t c : utf16) std::cout << std::hex << std::showbase << c << '\n'; // the UTF-8 / UTF-32 standard conversion facet std::u32string utf32 = std::wstring_con- vert<std::codecvt_utf8<char32_t>, char32_t>{}.from_bytes(utf8); std::cout << "UTF32 conversion produced " << std::dec << utf32.size() << " code units:\n"; for (char32_t c : utf32) std::cout << std::hex << std::showbase << c << '\n'; } Output: UTF16 conversion produced 5 code units: 0x7a 0xdf 0x6c34 0xd834 0xdd0b UTF32 conversion produced 4 code units: 0x7a 0xdf 0x6c34 0x1d10b See also to_bytes converts a wide string into a byte string (public member function) mbsrtowcs converts a narrow multibyte character string to wide string, given state (function) do_in converts a string from externT to internT, such as when reading from file [virtual] (virtual protected member function of std::codecvt<In- ternT,ExternT,State>) http://cppreference.com 2022.07.31 std::wstrin...:from_bytes(3)
NAME | Synopsis | Return value | Exceptions | Example | Output: | See also
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