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std::mbrlen

Da cppreference.com
< cpp‎ | string‎ | multibyte

 
 
Biblioteca cordas
Strings terminadas
Original:
Null-terminated strings
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Cadeias de bytes
Multibyte cordas
Cordas de largura
Classes
Original:
Classes
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basic_string
char_traits
 
Strings terminadas multibyte
Wide / multibyte conversões
Original:
Wide/multibyte conversions
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mbsinit
Tipos
Original:
Types
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mbstate_t
 
Defined in header <cwchar>
std::size_t mbrlen( const char* s, std::size_t n, std::mbstate_t* ps);
Determina o tamanho, em bytes, do restante do caractere multibyte cujo primeiro byte é apontado por s, dado o estado de conversão atual ps.
Original:
Determines the size, in bytes, of the remainder of the multibyte character whose first byte is pointed to by s, given the current conversion state ps.
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Esta função é equivalente à std::mbrtowc(nullptr, s, n, ps?ps:&internal) chamada para internal objeto escondido de std::mbstate_t tipo, exceto que o ps expressão é avaliada apenas uma vez.
Original:
This function is equivalent to the call std::mbrtowc(nullptr, s, n, ps?ps:&internal) for some hidden object internal of type std::mbstate_t, except that the expression ps is evaluated only once.
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Índice

[editar] Parâmetros

s -
ponteiro para um elemento de uma cadeia de caracteres multibyte
Original:
pointer to an element of a multibyte character string
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n -
limitar o número de bytes em s que podem ser examinados
Original:
limit on the number of bytes in s that can be examined
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ps -
ponteiro para a variável que contém o estado de conversão
Original:
pointer to the variable holding the conversion state
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[editar] Valor de retorno

0 se o n seguinte ou menos bytes completar o caractere nulo.
Original:
0 if the next n or fewer bytes complete the null character.
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O número de bytes (entre 1 e n) que completam um caractere multibyte válido
Original:
The number of bytes (between 1 and n) that complete a valid multibyte character
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(size_t)-1 se ocorre erro de codificação
Original:
(size_t)-1 if encoding error occurs
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(size_t)-2 se os bytes n próximos são parte de um caractere multibyte possivelmente válidos, que ainda está incompleta depois de examinar todos os bytes n
Original:
(size_t)-2 if the next n bytes are part of a possibly valid multibyte character, which is still incomplete after examining all n bytes
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[editar] Exemplo

#include <clocale>
#include <string>
#include <iostream>
#include <cwchar>
 
int main()
{
    // allow mbrlen() to work with UTF-8 multibyte encoding
    std::setlocale(LC_ALL, "en_US.utf8");
    // UTF-8 narrow multibyte encoding
    std::string str = u8"水"; // or u8"\u6c34" or "\xe6\xb0\xb4"
    std::mbstate_t mb = std::mbstate_t();
    int len1 = std::mbrlen(&str[0], 1, &mb);
    if(len1 == -2) {
        std::cout << "The first 1 byte of " << str
                  << " is an incomplete multibyte char (mbrlen returns -2)\n";
    }
    int len2 = std::mbrlen(&str[1], str.size()-1, &mb);
    std::cout << "The remaining " << str.size()-1 << " bytes of " << str
              << " hold " << len2 << " bytes of the multibyte character\n";
    std::cout << "Attempting to call mbrlen() in the middle of " << str
              << " while in initial shift state returns "
              << (int)mbrlen(&str[1], str.size(), &mb) << '\n';
 
}

Output:

The first 1 byte of 水 is an incomplete multibyte char (mbrlen returns -2)
The remaining 2 bytes of 水 hold 2 bytes of the multibyte character
Attempting to call mbrlen() in the middle of 水 while in initial shift state returns -1

[editar] Veja também

converte o caractere multibyte ao lado de caráter amplo, determinado estado
Original:
converts the next multibyte character to wide character, given state
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(função) [edit]
retorna o número de bytes no caractere multibyte seguinte
Original:
returns the number of bytes in the next multibyte character
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(função) [edit]
[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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(virtual protegido of std::codecvt função de membro) [edit]
C documentation for mbrlen