Defined in header <codecvt> | ||
---|---|---|
template< class Elem, unsigned long Maxcode = 0x10ffff, std::codecvt_mode Mode = (std::codecvt_mode)0 > class codecvt_utf16 : public std::codecvt<Elem, char, std::mbstate_t>;; |
std::codecvt_utf16
is a std::codecvt
facet which encapsulates conversion between a UTF-16 encoded byte string and UCS2 or UCS4 character string (depending on the type of Elem
). This codecvt facet can be used to read and write UTF-16 files in binary mode.
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_utf16 facet (public member function) |
(destructor) | destroys a codecvt_utf16 facet (public member function) |
std::codecvt_utf16::codecvt_utf16
explicit codecvt_utf16( std::size_t refs = 0 ); |
Constructs a new std::codecvt_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_utf16::~codecvt_utf16
~codecvt_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 decoding of UTF-16le file on a system with 32-bit wchar_t
. On a system with 16-bit wchar_t
, decoding of the third character will fail because std::codecvt_utf16<char16_t>
produces UCS2, not UTF-16.
#include <fstream> #include <iostream> #include <string> #include <locale> #include <codecvt> void prepare_file() { // UTF-16le data (if host system is little-endian) char16_t utf16le[4] ={0x007a, // latin small letter 'z' U+007a 0x6c34, // CJK ideograph "water" U+6c34 0xd834, 0xdd0b}; // musical sign segno U+1d10b // store in a file std::ofstream fout("text.txt"); fout.write( reinterpret_cast<char*>(utf16le), sizeof utf16le); } int main() { prepare_file(); // open as a byte stream std::wifstream fin("text.txt", std::ios::binary); // apply facet fin.imbue(std::locale(fin.getloc(), new std::codecvt_utf16<wchar_t, 0x10ffff, std::little_endian>)); for (wchar_t c; fin.get(c); ) std::cout << std::showbase << std::hex << c << '\n'; }
Output:
0x7a 0x6c34 0x1d10b
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-8 and UTF-16 (class template) |
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