std::codecvt<InternT,ExternT,StateT>:: max_length, do_max_length

Valeur de retour

Le nombre maximum de caractères ExternT qui pourraient être consommés si convertis par in() pour produire un caractère InternT .

La spécialisation non-convertissante std:: codecvt < char , char , std:: mbstate_t > retourne 1 .

Notes

Si l'encodage dépend de l'état ( encoding ( ) == - 1 ), alors plus de max_length() caractères externes peuvent être consommés pour produire un caractère interne.

Exemple

#include <codecvt>
#include <iostream>
#include <locale>
int main()
{
    std::cout << "In codecvt_utf8, the longest multibyte character is "
              << std::codecvt_utf8<wchar_t>().max_length() << " bytes long\n";
    std::cout << "In header-consuming codecvt_utf8, the longest multibyte character is "
              << std::codecvt_utf8<wchar_t,
                                   0x10ffff,
                                   std::consume_header>().max_length() << " bytes long\n";
    std::cout << "In this system's en_US.utf8, the longest multibyte character is "
              << std::use_facet<std::codecvt<wchar_t, char, std::mbstate_t>>(
                     std::locale("en_US.utf8")
                 ).max_length() << " bytes long\n";
    std::cout << "In this system's zh_CN.gb18030, the longest multibyte character is "
              << std::use_facet<std::codecvt<wchar_t, char, std::mbstate_t>>(
                     std::locale("zh_CN.gb18030")
                 ).max_length() << " bytes long\n";
}

In codecvt_utf8, the longest multibyte character is 4 bytes long
In header-consuming codecvt_utf8, the longest multibyte character is 7 bytes long
In this system's en_US.utf8, the longest multibyte character is 6 bytes long
In this system's zh_CN.gb18030, the longest multibyte character is 4 bytes long

Voir aussi