std::codecvt::length, std::codecvt::do_length
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public: int length( stateT& state, const externT* from, const externT* from_end, std::size_t max ) const |
(1) | |
protected: int do_length( stateT& state, const externT* from, const externT* from_end, std::size_t max ) const |
(2) | |
1)
função de membro público, chama a
do_length função de membro da classe derivada mais.Original:
public member function, calls the member function
do_length of the most derived class.The text has been machine-translated via Google Translate.
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2)
tentativas de converter os personagens
externT da matriz de caracteres definidos pelo [from, from_end), dado state estado inicial de conversão, para a maioria dos max internT caracteres, e retorna o número de caracteres que a conversão externT tal consomem. Modifica state como se executando do_in(state, from, from_end, from, to, to+max, to) para algum buffer imaginário [to, to+max) saída.Original:
attempts to convert the
externT characters from the character array defined by [from, from_end), given initial conversion state state, to at most max internT characters, and returns the number of externT characters that such conversion would consume. Modifies state as if by executing do_in(state, from, from_end, from, to, to+max, to) for some imaginary [to, to+max) output buffer.The text has been machine-translated via Google Translate.
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Valor de retorno
O número de caracteres
externT que seria consumido se convertido por do_in() até que todos os personagens from_end-from foram consumidos ou max internT personagens eram produtor, ou um erro de conversão ocorreu.Original:
The number of
externT characters that would be consumed if converted by do_in() until either all from_end-from characters were consumed or max internT characters were producer, or a conversion error occurred.The text has been machine-translated via Google Translate.
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A especialização não-conversão
std::codecvt<char, char, std::mbstate_t> retornos std::min(max, from_end-from)Original:
The non-converting specialization
std::codecvt<char, char, std::mbstate_t> returns std::min(max, from_end-from)The text has been machine-translated via Google Translate.
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Exemplo
#include <locale>
#include <string>
#include <iostream>
int main()
{
// narrow multibyte encoding
std::string s = "z\u00df\u6c34\U0001d10b"; // or u8"zß水𝄋"
// or "\x7a\xc3\x9f\xe6\xb0\xb4\xf0\x9d\x84\x8b";
std::mbstate_t mb = std::mbstate_t();
std::cout << "Only the first " <<
std::use_facet<std::codecvt<wchar_t, char, std::mbstate_t>>(
std::locale("en_US.utf8")
).length(mb, &s[0], &s[s.size()], 2)
<< " bytes out of " << s.size() << " would be consumed "
" to produce the first 2 characters\n";
}
Saída:
Only the first 3 bytes out of 10 would be consumed to produce the first 2 characters
Veja também
[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 The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (virtual protegido função de membro) |