std::codecvt_byname
Defined in header <locale> |
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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.
Following specializations are provided by the standard library.
Defined in header <locale> |
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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)(deprecated in C++20) |
std::codecvt_byname<char16_t, char8_t, std::mbstate_t> |
conversion between UTF-16 and UTF-8 (since C++20) |
std::codecvt_byname<char32_t, char, std::mbstate_t> |
conversion between UTF-32 and UTF-8 (since C++11)(deprecated in C++20) |
std::codecvt_byname<char32_t, char8_t, std::mbstate_t> |
conversion between UTF-32 and UTF-8 (since C++20) |
std::codecvt_byname<wchar_t, char, std::mbstate_t> |
locale-specific conversion between wide string and narrow character sets |
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 ); |
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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 |
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id (static) |
std::locale::id |
Member functions
invokes do_out (public member function of std::codecvt<InternT,ExternT,State> ) |
|
invokes do_in (public member function of std::codecvt<InternT,ExternT,State> ) |
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invokes do_unshift (public member function of std::codecvt<InternT,ExternT,State> ) |
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invokes do_encoding (public member function of std::codecvt<InternT,ExternT,State> ) |
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invokes do_always_noconv (public member function of std::codecvt<InternT,ExternT,State> ) |
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invokes do_length (public member function of std::codecvt<InternT,ExternT,State> ) |
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invokes do_max_length (public member function of std::codecvt<InternT,ExternT,State> ) |
Protected member functions
[virtual]
|
converts a string from internT to externT, such as when writing to file (virtual protected member function of std::codecvt<InternT,ExternT,State> ) |
[virtual]
|
converts a string from externT to internT, such as when reading from file (virtual protected member function of std::codecvt<InternT,ExternT,State> ) |
[virtual]
|
generates the termination character sequence of externT characters for incomplete conversion (virtual protected member function of std::codecvt<InternT,ExternT,State> ) |
[virtual]
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returns the number of externT characters necessary to produce one internT character, if constant (virtual protected member function of std::codecvt<InternT,ExternT,State> ) |
[virtual]
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tests if the facet encodes an identity conversion for all valid argument values (virtual protected member function of std::codecvt<InternT,ExternT,State> ) |
[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<InternT,ExternT,State> ) |
[virtual]
|
returns the maximum number of externT characters that could be converted into a single internT character (virtual protected member function of std::codecvt<InternT,ExternT,State> ) |
Inherited from std::codecvt_base
Member type | Definition |
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enum result { ok, partial, error, noconv }; |
Unscoped enumeration type |
Enumeration constant | Definition |
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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 |
Example
This example demonstrates reading a GB18030-encoded file using the codecvt facet from a GB18030-aware locale.
#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
See also
converts between character encodings, including UTF-8, UTF-16, UTF-32 (class template) |
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