std::codecvt_byname
From cppreference.com
Defined in header
<locale>
|
||
template< class InternT, class ExternT, class State >
class codecvt_byname : public std::codecvt<InternT, ExternT, State>; |
||
std::codecvt_byname is a std::codecvt facet which encapsulates multibyte/wide character conversion rules of a locale specified at its construction.
Four specializations are provided by the standard library
Defined in header
<locale> |
|
std::codecvt_byname<char, char, std::mbstate_t> | identity conversion |
std::codecvt_byname<char16_t, char, std::mbstate_t> | conversion between UTF-16 and UTF-8 (since C++11) |
std::codecvt_byname<char32_t, char, std::mbstate_t> | conversion between UTF-32 and UTF-8 (since C++11) |
std::codecvt_byname<wchar_t, char, std::mbstate_t> | locale-specific conversion between wide string and narrow, possibly multibyte, string |
Contents |
[edit] Member functions
(constructor) |
constructs a new codecvt_byname facet (public member function) |
(destructor) |
destroys a codecvt_byname facet (protected member function) |
std::codecvt_byname::codecvt_byname
explicit codecvt_byname( const char* name, std::size_t refs = 0 );
|
||
explicit codecvt_byname( const std::string& name, std::size_t refs = 0 );
|
(since C++11) | |
Constructs a new std::codecvt_byname
facet for a locale with name
.
refs
is used for resource management: if refs == 0, the implementation destroys the facet, when the last std::locale object holding it is destroyed. Otherwise, the object is not destroyed.
Parameters
name | - | the name of the locale |
refs | - | the number of references that link to the facet |
std::codecvt_byname::~codecvt_byname
protected:
~codecvt_byname(); |
||
Destroys the facet.
Inherited from std::codecvt
Member types
Member type | Definition |
intern_type
|
internT
|
extern_type
|
externT
|
state_type
|
stateT
|
Member objects
Member name | Type |
id (static)
|
std::locale::id |
Member functions
invokes do_out (public member function of std::codecvt )
|
|
invokes do_in (public member function of std::codecvt )
|
|
invokes do_unshift (public member function of std::codecvt )
|
|
invokes do_encoding (public member function of std::codecvt )
|
|
invokes do_always_noconv (public member function of std::codecvt )
|
|
invokes do_length (public member function of std::codecvt )
|
|
invokes do_max_length (public member function of std::codecvt )
|
Protected member functions
[virtual]
|
converts a string from internT to externT, such as when writing to file (virtual protected member function of std::codecvt )
|
[virtual]
|
converts a string from externT to internT, such as when reading from file (virtual protected member function of std::codecvt )
|
[virtual]
|
generates the termination character sequence of externT characters for incomplete conversion (virtual protected member function of std::codecvt )
|
[virtual]
|
returns the number of externT characters necessary to produce one internT character, if constant (virtual protected member function of std::codecvt )
|
[virtual]
|
tests if the facet encodes an identity conversion for all valid argument values (virtual protected member function of std::codecvt )
|
[virtual]
|
calculates the length of the externT string that would be consumed by conversion into given internT buffer (virtual protected member function of std::codecvt )
|
[virtual]
|
returns the maximum number of externT characters that could be converted into a single internT character (virtual protected member function of std::codecvt )
|
Inherited from std::codecvt_base
Member type | Definition |
enum result { ok, partial, error, noconv }; | Unscoped enumeration type |
Enumeration constant | Definition |
ok
|
conversion was completed with no error |
partial
|
not all source characters were converted |
error
|
encountered an invalid character |
noconv
|
no conversion required, input and output types are the same |
[edit] Example
This example demonstrates reading a GB18030-encoded file using the codecvt facet from a GB18030-aware locale
Run this code
#include <iostream> #include <fstream> #include <string> #include <locale> int main() { // GB18030 narrow multibyte encoding std::ofstream("text.txt") << "\x7a" // letter 'z', U+007a "\x81\x30\x89\x38" // letter 'ß', U+00df "\xcb\xae" // CJK ideogram '水' (water), U+6c34 "\x94\x32\xbc\x35"; // musical sign '𝄋' (segno), U+1d10b std::wifstream fin("text.txt"); fin.imbue(std::locale(fin.getloc(), new std::codecvt_byname<wchar_t, char, std::mbstate_t>("zh_CN.gb18030"))); for (wchar_t c; fin.get(c); ) std::cout << std::hex << std::showbase << c << '\n'; }
Output:
0x7a 0xdf 0x6c34 0x1d10b
[edit] See also
converts between character encodings, including UTF-8, UTF-16, UTF-32 (class template) |