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std::codecvt_utf8 - cppreference.com

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Definido no cabeçalho

<codecvt>

template< class Elem, unsigned long Maxcode = 0x10ffff, std::codecvt_mode Mode = (std::codecvt_mode)0 > class codecvt_utf8 : public std::codecvt<Elem, char, std::mbstate_t>;

std::codecvt_utf8 é uma faceta std::codecvt que encapsula a conversão entre uma cadeia de caracteres UTF-8 byte codificado e UCS2 ou UCS4 cadeia de caracteres (dependendo do tipo de Elem). Esta faceta codecvt pode ser usado para ler e escrever arquivos UTF-8, texto e binário.

Original:

std::codecvt_utf8 is a std::codecvt facet which encapsulates conversion between a UTF-8 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-8 files, both text and binary.

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Parâmetros do modelo

Elem -

ou char16_t, char32_t, wchar_t ou

Original:

either char16_t, char32_t, or wchar_t

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Maxcode -

o maior valor de Elem que esta faceta irá ler ou escrever sem erro

Original:

the largest value of Elem that this facet will read or write without error

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Mode -

uma constante de std::codecvt_mode tipo

Original:

a constant of type std::codecvt_mode

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Herdado de std::codecvt

Member types

Tipo de membro

Original:

Member type

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 Definition
intern_type internT
extern_type externT
state_type stateT

Member objects

Nome do membro

Original:

Member name

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 Type
id (estática) std::locale::id

Member functions

Invoca do_out

Original:

invokes do_out

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(of std::codecvt função pública membro) [edit]

Invoca do_in

Original:

invokes do_in

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(of std::codecvt função pública membro) [edit]

Invoca do_unshift

Original:

invokes do_unshift

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(of std::codecvt função pública membro) [edit]

Invoca do_encoding

Original:

invokes do_encoding

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(of std::codecvt função pública membro) [edit]

Invoca do_always_noconv

Original:

invokes do_always_noconv

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(of std::codecvt função pública membro) [edit]

Invoca do_length

Original:

invokes do_length

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(of std::codecvt função pública membro) [edit]

Invoca do_max_length

Original:

invokes do_max_length

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(of std::codecvt função pública membro) [edit]

Protected member functions

[virtual]

Converte uma cadeia de internt para externT, como ao escrever para o arquivo

Original:

converts a string from internT to externT, such as when writing to file

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(virtual protegido of std::codecvt função de membro) [edit]

[virtual]

Converte uma cadeia de externT a Internt, como quando lendo de um arquivo

Original:

converts a string from externT to internT, such as when reading from file

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(virtual protegido of std::codecvt função de membro) [edit]

[virtual]

gera a seqüência de caracteres de terminação de caracteres externT para conversão incompleta

Original:

generates the termination character sequence of externT characters for incomplete conversion

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[virtual]

retorna o número de caracteres externT necessários para produzir um caráter internt, se constante

Original:

returns the number of externT characters necessary to produce one internT character, if constant

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Testes se a faceta codifica uma conversão de identidade para todos os valores de argumentos válidos

Original:

tests if the facet encodes an identity conversion for all valid argument values

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[virtual]

calcula o comprimento da corda externT que seria consumida por conversão em tampão internt dado

Original:

calculates the length of the externT string that would be consumed by conversion into given internT buffer

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devolve o número máximo de caracteres externT que poderia ser convertido em um único caractere internt

Original:

returns the maximum number of externT characters that could be converted into a single internT character

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Herdado de std::codecvt_base

Tipo de membro

Original:

Member type

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 Definition
enum result { ok, partial, error, noconv };

Tipo de enumeração sem escopo

Original:

Unscoped enumeration type

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Enumeração constante

Original:

Enumeration constant

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 Definition
ok

conversão foi completado sem qualquer erro

Original:

conversion was completed with no error

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partial

nem todos os caracteres de fonte foram convertidos

Original:

not all source characters were converted

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error

encontrou um caractere inválido

Original:

encountered an invalid character

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noconv

necessária nenhuma conversão de entrada, e os tipos de saída são os mesmos

Original:

no conversion required, input and output types are the same

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Exemplo

O exemplo a seguir demonstra a diferença entre UCS2/UTF-8 e UTF-16/UTF-8 conversões: o terceiro personagem na cadeia não é um personagem UCS2 válido .

Original:

The following example demonstrates the difference between UCS2/UTF-8 and UTF-16/UTF-8 conversions: the third character in the string is not a valid UCS2 character.

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#include <iostream>
#include <string>
#include <locale>
#include <codecvt>
int main()
{
    // UTF-8 data. The character U+1d10b, musical sign segno, does not fit in UCS2
    std::string utf8 = u8"z\u6c34\U0001d10b";

    // the UTF-8 / UTF-16 standard conversion facet
    std::wstring_convert<std::codecvt_utf8_utf16<char16_t>, char16_t> utf16conv;
    std::u16string utf16 = utf16conv.from_bytes(utf8);
    std::cout << "UTF16 conversion produced " << utf16.size() << " code points:\n";
    for(char16_t c : utf16)
        std::cout << std::hex << std::showbase << c << '\n';

    // the UTF-8 / UCS2 standard conversion facet
    std::wstring_convert<std::codecvt_utf8<char16_t>, char16_t> ucs2conv;
    try {
        std::u16string ucs2 = ucs2conv.from_bytes(utf8);
    } catch(const std::range_error& e) {
        std::u16string ucs2 = ucs2conv.from_bytes(utf8.substr(0, ucs2conv.converted()));
        std::cout << "UCS2 failed after producing " << std::dec << ucs2.size()<<" characters:\n";
        for(char16_t c : ucs2)
            std::cout << std::hex << std::showbase << c << '\n';
    }
}

Saída: 

UTF16 conversion produced 4 code points:
0x7a
0x6c34
0xd834
0xdd0b
UCS2 failed after producing 2 characters:
0x7a
0x6c34

Veja também

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

Converte entre codificações de caracteres, incluindo UTF-8, UTF-16, UTF-32

Original:

converts between character encodings, including UTF-8, UTF-16, UTF-32

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(modelo de classe) [edit]

etiquetas para alterar o comportamento das facetas codecvt padrão

Original:

tags to alter behavior of the standard codecvt facets

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(classe) [edit]

converte entre UTF-16 e UCS2/UCS4

Original:

converts between UTF-16 and UCS2/UCS4

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(modelo de classe) [edit]
converts between UTF-8 and UTF-16
(modelo de classe) [edit]