std::mbrlen – cppreference.com

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definiert in Header `<cwchar>`

`std::size_t mbrlen( const char* s, std::size_t n, std::mbstate_t* ps);`

Bestimmt die Größe in Bytes, der Rest des Multibyte-Zeichen, dessen erstes Byte wird durch s hingewiesen, angesichts der aktuellen Konvertierungsstatus 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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Diese Funktion entspricht dem Aufruf std::mbrtowc(nullptr, s, n, ps?ps:&internal) für einige versteckte Objekt internal vom Typ std::mbstate_t, außer, dass der Ausdruck ps nur einmal ausgewertet wird .

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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Parameter

s	-	Zeiger auf ein Element einer Multibyte Zeichenkette 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	-	Grenze für die Anzahl von Bytes in s, die untersucht werden können 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	-	Zeiger auf die Variable, die die Umwandlung Zustand 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.

Rückgabewert

0 wenn die nächste n oder weniger Bytes die Null-Zeichen abgeschlossen .

Original:

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

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Die Anzahl der Bytes (zwischen 1 und n) ausfüllen, dass ein gültiges Multibyte-Zeichen

Original:

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

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(size_t)-1 wenn die Kodierung Fehler auftritt

Original:

(size_t)-1 if encoding error occurs

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(size_t)-2 wenn die nächsten n bytes Teil eines möglicherweise gültiges Multibyte-Zeichen, die noch unvollständig ist nach Prüfung aller n Byte sind

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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Beispiel

#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

Siehe auch


mbrtowc	wandelt die nächsten Multibyte Zeichen-Zeichen, gegebenen Zustand 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. (Funktion) [edit]

mblen	gibt die Anzahl der Bytes in den nächsten Multibyte-Zeichens 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. (Funktion) [edit]

do_length [virtuell]	berechnet die Länge der Zeichenfolge, externT durch Umwandlung in gegebenen Internt Puffer verbraucht würde 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. (virtuellen geschützten Member-Funktion of `std::codecvt`) [edit]

C documentation for mbrlen