NAME¶

std::wcstombs - std::wcstombs

Synopsis¶

Defined in header <cstdlib>
std::size_t wcstombs( char* dst, const wchar_t* src, std::size_t len );

Converts a sequence of wide characters from the array whose first element is pointed
to by src to its narrow multibyte representation that begins in the initial shift
state. Converted characters are stored in the successive elements of the char array
pointed to by dst. No more than len bytes are written to the destination array.

Each character is converted as if by a call to std::wctomb, except that the wctomb's
conversion state is unaffected. The conversion stops if:

* The null character was converted and stored.
* A wchar_t was found that does not correspond to a valid character in the current
C locale.
* The next multibyte character to be stored would exceed len.

Notes¶

In most implementations, this function updates a global static object of type
std::mbstate_t as it processes through the string, and cannot be called
simultaneously by two threads, std::wcsrtombs should be used in such cases.

POSIX specifies a common extension: if dst is a null pointer, this function returns
the number of bytes that would be written to dst, if converted. Similar behavior is
standard for std::wcsrtombs.

Parameters¶

dst - pointer to narrow character array where the multibyte character will be stored
src - pointer to the first element of a null-terminated wide string to convert
len - number of byte available in the array pointed to by dst

Return value¶

On success, returns the number of bytes (including any shift sequences, but
excluding the terminating '\0') written to the character array whose first element
is pointed to by dst.

On conversion error (if invalid wide character was encountered), returns
static_cast<std::size_t>(-1).

Example¶

// Run this code

#include <clocale>
#include <cstdlib>
#include <iostream>

int main()
{
std::setlocale(LC_ALL, "en_US.utf8");
// UTF-8 narrow multibyte encoding
const wchar_t* wstr = L"z\u00df\u6c34\U0001d10b"; // or L"zß水𝄋"
char mbstr[11];
std::wcstombs(mbstr, wstr, 11);
std::cout << "multibyte string: " << mbstr << '\n';
}

Output:¶

multibyte string: zß水𝄋

See also¶

wcsrtombs converts a wide string to narrow multibyte character string, given state
(function)
mbstowcs converts a narrow multibyte character string to wide string
(function)
do_out converts a string from InternT to ExternT, such as when writing to file
[virtual] (virtual protected member function of
std::codecvt<InternT,ExternT,StateT>)
C documentation for
wcstombs