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std::codecvt_utf8_utf16

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Defined in header <codecvt>
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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>;
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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.

Contents

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

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) [edit]
invokes do_in
(public member function of std::codecvt) [edit]
invokes do_unshift
(public member function of std::codecvt) [edit]
invokes do_encoding
(public member function of std::codecvt) [edit]
invokes do_always_noconv
(public member function of std::codecvt) [edit]
invokes do_length
(public member function of std::codecvt) [edit]
invokes do_max_length
(public member function of std::codecvt) [edit]

Protected member functions

[virtual]
converts a string from internT to externT, such as when writing to file
(virtual protected member function of std::codecvt) [edit]
[virtual]
converts a string from externT to internT, such as when reading from file
(virtual protected member function of std::codecvt) [edit]
[virtual]
generates the termination character sequence of externT characters for incomplete conversion
(virtual protected member function of std::codecvt) [edit]
[virtual]
returns the number of externT characters necessary to produce one internT character, if constant
(virtual protected member function of std::codecvt) [edit]
tests if the facet encodes an identity conversion for all valid argument values
(virtual protected member function of std::codecvt) [edit]
[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) [edit]
returns the maximum number of externT characters that could be converted into a single internT character
(virtual protected member function of std::codecvt) [edit]


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 / c16rtomb codecvt<char16_t, char, mbstate_t>
codecvt_utf8_utf16<char16_t>
codecvt_utf8_utf16<char32_t>
codecvt_utf8_utf16<wchar_t>
N/A
UCS2 No 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
Template:cpp/locale/dcl list codecvtTemplate:cpp/locale/dcl list codecvt modeTemplate:cpp/locale/dcl list codecvt utf8Template:cpp/locale/dcl list codecvt utf16