std::codecvt

From Cppreference

Defined in header `<locale>`

template< class internT, class externT, class stateT > class codecvt;

Class std::codecvt encapsulates conversion of character strings, including wide and multibyte, from one encoding to another. All file I/O operations performed through std::basic_fstream<CharT> use the std::codecvt<CharT, char, std::mbstate_t> facet of the locale imbued in the stream.

Four specializations are provided by the standard library and are implemented by all locale objects created in a C++ program:

Defined in header `<locale>`

std::codecvt<char, char, std::mbstate_t>	identity conversion

std::codecvt<char16_t, char, std::mbstate_t>	conversion between UTF-16 and UTF-8 (C++11 feature)

std::codecvt<char32_t, char, std::mbstate_t>	conversion between UTF-32 and UTF-8 (C++11 feature)

std::codecvt<wchar_t, char, std::mbstate_t>	locale-specific conversion between wide string and narrow, possibly multibyte, string

Inherited from std::codecvt_base


Type	Definition

`result`	conversion status enumeration type, defining the values `ok`, `partial`, `error`, and `noconv`

[edit] Example

The following examples reads a UTF-8 file using a locale which implements UTF-8 conversion in codecvt<wchar_t, char, mbstate_t>

#include <iostream>
#include <fstream>
#include <string>
#include <locale>
#include <iomanip>
int main()
{
    // UTF-8 narrow multibyte encoding
    std::ofstream("text.txt") << u8"z\u00df\u6c34\U0001d10b"; // or u8"zß水𝄋"
                                           // or "\x7a\xc3\x9f\xe6\xb0\xb4\xf0\x9d\x84\x8b";
    std::wifstream fin("text.txt");
    fin.imbue(std::locale("en_US.UTF-8")); // this locale's codecvt<wchar_t, char, mbstate_t>
                                           // converts UTF-8 to UCS4
    std::cout << "The UTF-8 file contains the following wide characters: \n";
    for(wchar_t c; fin >> c; )
        std::cout << "U+" << std::hex << std::setw(4) << std::setfill('0') << c << '\n';
}

Output:

The UTF-8 file contains the following wide characters:
U+007a
U+00df
U+6c34
U+1d10b

[edit] See also

Character conversions	narrow multibyte (char)	UTF-8 (char)	UTF-16 (char16_t)
UTF-16	`mbrtoc16` / `c16rtombr`	`codecvt`<char16_t, char, mbstate_t> `codecvt_utf8_utf16`<char16_t> `codecvt_utf8_utf16`<char32_t> `codecvt_utf8_utf16`<wchar_t>	N/A
UCS2	No	`codecvt_utf8`<char16_t>	`codecvt_utf16`<char16_t>
UTF-32/UCS4 (char32_t)	`mbrtoc32` / `c32rtombr`	`codecvt`<char32_t, char, mbstate_t> `codecvt_utf8`<char32_t>	`codecvt_utf16`<char32_t>
UCS2/UCS4 (wchar_t)	No	`codecvt_utf8`<wchar_t>	`codecvt_utf16`<wchar_t>
wide (wchar_t)	`codecvt`<wchar_t, char, mbstate_t> `mbstowcs` / `wcstombs`	No	No

codecvt_base

defines character conversion errors
(class template)

codecvt_byname

creates a codecvt facet for the named locale
(class template)

codecvt_utf8 (C++11)

converts between UTF-8 and UCS2/UCS4
(class template)

codecvt_utf16 (C++11)

converts between UTF-16 and UCS2/UCS4
(class template)

codecvt_utf8_utf16 (C++11)

converts between UTF-8 and UTF-16
(class template)


Member type	Definition

`intern_type`	`internT`

`extern_type`	`externT`

`state_type`	`stateT`


Member name	Type

`id` (static)	std::locale::id

std::codecvt

From Cppreference

Contents

[edit] Member types

[edit] Member objects

[edit] Member functions

Public member functions (pubic interface)

Virtual member functions (can be overridden in a user-defined facet derived from codecvt

Inherited from std::codecvt_base

[edit] Example

[edit] See also