std::mbrtowc - cppreference.com (original) (raw)
Converts a narrow multibyte character to a wide character.
If s is not a null pointer, inspects at most n bytes of the multibyte character string, beginning with the byte pointed to by s to determine the number of bytes necessary to complete the next multibyte character (including any shift sequences). If the function determines that the next multibyte character in s is complete and valid, converts it to the corresponding wide character and stores it in *pwc (if pwc is not null).
If s is a null pointer, the values of n and pwc are ignored and call is equivalent to std::mbrtowc(nullptr, "", 1, ps).
If the wide character produced is the null character, the conversion state stored in *ps is the initial shift state.
[edit] Parameters
| pwc | - | pointer to the location where the resulting wide character will be written |
|---|---|---|
| s | - | pointer to the multibyte character string used as input |
| n | - | limit on the number of bytes in s that can be examined |
| ps | - | pointer to the conversion state used when interpreting the multibyte string |
[edit] Return value
The first of the following that applies:
- 0 if the character converted from s (and stored in pwc if non-null) was the null character.
- the number of bytes [1...n] of the multibyte character successfully converted from s.
- static_cast<std::size_t>(-2) if the next n bytes constitute an incomplete, but so far valid, multibyte character. Nothing is written to *pwc.
- static_cast<std::size_t>(-1) if encoding error occurs. Nothing is written to *pwc, the value EILSEQ is stored in errno and the value of *ps is left unspecified.
[edit] Example
#include #include #include #include void print_mb(const char* ptr) { std::mbstate_t state = std::mbstate_t(); // initial state const char* end = ptr + std::strlen(ptr); int len; wchar_t wc; while ((len = std::mbrtowc(&wc, ptr, end-ptr, &state)) > 0) { std::wcout << "Next " << len << " bytes are the character " << wc << '\n'; ptr += len; } } int main() { std::setlocale(LC_ALL, "en_US.utf8"); // UTF-8 narrow multibyte encoding const char* str = "z\u00df\u6c34\U0001d10b"; // or u8"zß水𝄋" // or "\x7a\xc3\x9f\xe6\xb0\xb4\xf0\x9d\x84\x8b"; print_mb(str); }
Output:
Next 1 bytes are the character z Next 2 bytes are the character ß Next 3 bytes are the character 水 Next 4 bytes are the character 𝄋
[edit] See also
| | converts the next multibyte character to wide character (function) [edit] | | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | | converts a wide character to its multibyte representation, given state (function) [edit] | | | converts a string from ExternT to InternT, such as when reading from file (virtual protected member function of std::codecvt<InternT,ExternT,StateT>) [edit] | | |