std::mbrlen — cppreference.com

De cppreference.com

Déclaré dans l'en-tête `<cwchar>`
`std::size_t mbrlen( const char* s, std::size_t n, std::mbstate_t* ps);`

Détermine la taille, en octets, du reste le caractère multi-octets dont le premier octet est pointé par s, étant donné l'état actuel de conversion 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.

The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.

Cette fonction est équivalente à la std::mbrtowc(nullptr, s, n, ps?ps:&internal) appel pour internal objets cachés std::mbstate_t type, sauf que le ps expression est évaluée une seule fois .

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.

The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.

Paramètres

s	-	pointeur sur un élément d'une chaîne de caractères multi-octets Original: pointer to an element of a multibyte character string The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
n	-	limiter le nombre d'octets dans s qui peut être examiné Original: limit on the number of bytes in s that can be examined The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
ps	-	pointeur vers la variable contenant l'état de conversion Original: pointer to the variable holding the conversion state The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.

Retourne la valeur

0 si le n suivante ou moins d'octets compléter le caractère nul .

Original:

0 if the next n or fewer bytes complete the null character.

The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.

Le nombre d'octets (entre 1 et n) qui complètent un caractère multi-octets valide

Original:

The number of bytes (between 1 and n) that complete a valid multibyte character

The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.

(size_t)-1 si erreur de codage survient

Original:

(size_t)-1 if encoding error occurs

The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.

(size_t)-2 si les octets n prochaines font partie d'un caractère multi-octets peut-être valable, ce qui est encore incomplète après avoir examiné tous les octets 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

The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.

Exemple

#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';

}

Résultat :

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

Voir aussi


mbrtowc	convertit le caractère multi-octets suivante caractère large, état donné Original: converts the next multibyte character to wide character, given state The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (fonction) [edit]

mblen	renvoie le nombre d'octets dans le prochain caractère multi-octets Original: returns the number of bytes in the next multibyte character The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (fonction) [edit]

do_length [ virtuel Original: virtual The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. ]	calcule la longueur de la chaîne Externt qui serait consommée par conversion en tampon Internt proposée Original: calculates the length of the externT string that would be consumed by conversion into given internT buffer The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (fonction membre virtuelle protégée de `std::codecvt`) [edit]

C documentation for mbrlen