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.
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
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.
Parameters
refs | - | the number of references that link to the facet |
std::codecvt_utf8_utf16::~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
.
#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
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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