| Defined in header <codecvt> | ||||
|---|---|---|---|---|
|
std::codecvt_utf8_utf16 is a std::codecvt facet which encapsulates conversion between a UTF-8 encoded byte string and UTF-16 encoded character string. If Elem is a 32-bit type, one UTF-16 codepoint will be stored in each 32-bit character of the output sequence. This codecvt facet can be used to read and write UTF-8 files, both text and binary.
Template Parameters
| Elem | - | either char16_t, char32_t, or wchar_t |
| Maxcode | - | the largest value of Elem that this facet will read or write without error |
| Mode | - | a constant of type std::codecvt_mode |
Member functions
| (constructor) | constructs a new codecvt_utf8_utf16 facet (public member function) |
| (destructor) | destroys a codecvt_utf8_utf16 facet (public member function) |
std::codecvt_utf8_utf16::codecvt_utf8_utf16
|
Constructs a new std::codecvt_utf8_utf16 facet, passes the initial reference counter refs to the base class.
Parameters
| refs | - | the number of references that link to the facet |
std::codecvt_utf8_utf16::~codecvt_utf8_utf16
|
Destroys the facet. Unlike the locale-managed facets, this facet's destructor is public.
Inherited from std::codecvt
Member types
| Member type | Definition |
|---|---|
intern_type | internT |
extern_type | externT |
state_type | stateT |
Member objects
| Member name | Type |
|---|---|
id (static) | std::locale::id |
Member functions
invokes do_out (public member function of std::codecvt) | |
invokes do_in (public member function of std::codecvt) | |
invokes do_unshift (public member function of std::codecvt) | |
invokes do_encoding (public member function of std::codecvt) | |
invokes do_always_noconv (public member function of std::codecvt) | |
invokes do_length (public member function of std::codecvt) | |
invokes do_max_length (public member function of std::codecvt) |
Protected member functions
| [virtual] | converts a string from internT to externT, such as when writing to file (virtual protected member function of std::codecvt) |
| [virtual] | converts a string from externT to internT, such as when reading from file (virtual protected member function of std::codecvt) |
| [virtual] | generates the termination character sequence of externT characters for incomplete conversion (virtual protected member function of std::codecvt) |
| [virtual] | returns the number of externT characters necessary to produce one internT character, if constant (virtual protected member function of std::codecvt) |
| [virtual] | tests if the facet encodes an identity conversion for all valid argument values (virtual protected member function of std::codecvt) |
| [virtual] | calculates the length of the externT string that would be consumed by conversion into given internT buffer (virtual protected member function of std::codecvt) |
| [virtual] | returns the maximum number of externT characters that could be converted into a single internT character (virtual protected member function of std::codecvt) |
Inherited from std::codecvt_base
| Member type | Definition |
|---|---|
enum result { ok, partial, error, noconv }; | Unscoped enumeration type |
| Enumeration constant | Definition |
|---|---|
ok | conversion was completed with no error |
partial | not all source characters were converted |
error | encountered an invalid character |
noconv | no conversion required, input and output types are the same |
Example
The following example demonstrates reading a UTF-8 file into a UTF-16 string on a system with 32-bit wchar_t.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 | #include <fstream>#include <iostream>#include <string>#include <locale>#include <codecvt> int main(){ std::ofstream("text.txt") << u8"z\u6c34\U0001d10b"; std::wifstream file1("text.txt"); file1.imbue(std::locale("en_US.UTF8")); std::cout << "Normal read from file (using default UTF-8/UTF-32 codecvt)\n"; for (wchar_t c; file1 >> c; ) std::cout << std::hex << std::showbase << c << '\n'; std::wifstream file2("text.txt"); file2.imbue(std::locale(file2.getloc(), new std::codecvt_utf8_utf16<wchar_t>)); std::cout << "UTF-16 read from the same file (using codecvt_utf8_utf16)\n"; for (wchar_t c; file2 >> c; ) std::cout << std::hex << std::showbase << c << '\n';} |
Output:
1 2 3 4 5 6 7 8 9 | Normal read from file (using default UTF-8/UTF-32 codecvt)0x7a0x6c340x1d10bUTF-16 read from the same file (using codecvt_utf8_utf16)0x7a0x6c340xd8340xdd0b |
See also
| Character conversions | narrow multibyte (char) | UTF-8 (char) | UTF-16 (char16_t) |
|---|---|---|---|
| UTF-16 | mbrtoc16(one way) | codecvt<char16_t, char, mbstate_t>codecvt_utf8_utf16<char16_t>codecvt_utf8_utf16<char32_t>codecvt_utf8_utf16<wchar_t> | N/A |
| UCS2 | c16rtomb(one way) | codecvt_utf8<char16_t> | codecvt_utf16<char16_t> |
| UTF-32/UCS4 (char32_t) | mbrtoc32 / c32rtomb | codecvt<char32_t, char, mbstate_t>codecvt_utf8<char32_t> | codecvt_utf16<char32_t> |
| UCS2/UCS4 (wchar_t) | No | codecvt_utf8<wchar_t> | codecvt_utf16<wchar_t> |
| wide (wchar_t) | codecvt<wchar_t, char, mbstate_t>mbsrtowcs / wcsrtombs | No | No |
| converts between character encodings, including UTF-8, UTF-16, UTF-32 (class template) | |
| (C++11) | tags to alter behavior of the standard codecvt facets (enum) |
| (C++11) | converts between UTF-8 and UCS2/UCS4 (class template) |
| (C++11) | converts between UTF-16 and UCS2/UCS4 (class template) |
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