std::codecvt_byname(3) | C++ Standard Libary | std::codecvt_byname(3) |
NAME¶
std::codecvt_byname - std::codecvt_byname
Synopsis¶
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.
Following specializations are provided by the standard library
Defined in header <locale>
std::codecvt_byname<char, char, identity conversion
std::mbstate_t>
std::codecvt_byname<char16_t, char, conversion between UTF-16 and UTF-8
(since
std::mbstate_t> C++11)(deprecated in C++20)
std::codecvt_byname<char16_t, char8_t, conversion between UTF-16 and UTF-8
(since
std::mbstate_t> C++20)
std::codecvt_byname<char32_t, char, conversion between UTF-32 and UTF-8
(since
std::mbstate_t> C++11)(deprecated in C++20)
std::codecvt_byname<char32_t, char8_t, conversion between UTF-32 and UTF-8
(since
std::mbstate_t> C++20)
std::codecvt_byname<wchar_t, char, locale-specific conversion between wide
std::mbstate_t> 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 );
explicit codecvt_byname( const std::string& name, std::size_t refs =
(since C++11)
0 );
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¶
out invokes do_out
(public member function of std::codecvt<InternT,ExternT,State>)
in invokes do_in
(public member function of std::codecvt<InternT,ExternT,State>)
unshift invokes do_unshift
(public member function of std::codecvt<InternT,ExternT,State>)
encoding invokes do_encoding
(public member function of std::codecvt<InternT,ExternT,State>)
always_noconv invokes do_always_noconv
(public member function of std::codecvt<InternT,ExternT,State>)
length invokes do_length
(public member function of std::codecvt<InternT,ExternT,State>)
max_length invokes do_max_length
(public member function of
std::codecvt<InternT,ExternT,State>)
Protected member functions¶
converts a string from internT to externT, such as when writing
to
do_out file
[virtual] (virtual protected member function
of
std::codecvt<InternT,ExternT,State>)
converts a string from externT to internT, such as when reading
do_in from file
[virtual] (virtual protected member
function of
std::codecvt<InternT,ExternT,State>)
generates the termination character sequence of externT characters
do_unshift for incomplete conversion
[virtual] (virtual protected member
function of
std::codecvt<InternT,ExternT,State>)
returns the number of externT characters necessary to produce one
do_encoding internT character, if constant
[virtual] (virtual protected member
function of
std::codecvt<InternT,ExternT,State>)
tests if the facet encodes an identity conversion for all valid
do_always_noconv argument values
[virtual] (virtual protected member
function of
std::codecvt<InternT,ExternT,State>)
calculates the length of the externT string that would be consumed
do_length by conversion into given internT buffer
[virtual] (virtual protected member
function of
std::codecvt<InternT,ExternT,State>)
returns the maximum number of externT characters that could be
do_max_length converted into a single internT character
[virtual] (virtual protected member
function of
std::codecvt<InternT,ExternT,State>)
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
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
See also¶
codecvt converts between character encodings, including UTF-8,
UTF-16, UTF-32
(class template)
2022.07.31 | http://cppreference.com |