| Defined in header
<codecvt> | ||
|---|---|---|
template< class Elem,
unsigned long Maxcode = 0x10ffff,
std::codecvt_mode Mode = (std::codecvt_mode)0 >
class codecvt_utf8_utf16 : public std::codecvt<Elem, char, std::mbstate_t>;
|
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.
| 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 |
| (constructor) | constructs a new codecvt_utf8_utf16 facet (public member function) |
| (destructor) | destroys a codecvt_utf8_utf16 facet (public member function) |
explicit codecvt_utf8_utf16( std::size_t refs = 0 ); |
Constructs a new std::codecvt_utf8_utf16 facet, passes the initial reference counter refs to the base class.
| refs | - | the number of references that link to the facet |
~codecvt_utf8_utf16(); |
Destroys the facet. Unlike the locale-managed facets, this facet's destructor is public.
| Member type | Definition |
|---|---|
intern_type | internT |
extern_type | externT |
state_type | stateT |
| Member name | Type |
|---|---|
id (static) | std::locale::id |
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) |
| [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) |
| 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 |
The following example demonstrates reading a UTF-8 file into a UTF-16 string on a system with 32-bit wchar_t.
#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:
Normal read from file (using default UTF-8/UTF-32 codecvt) 0x7a 0x6c34 0x1d10b UTF-16 read from the same file (using codecvt_utf8_utf16) 0x7a 0x6c34 0xd834 0xdd0b
| 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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