`<codecvt>`

[added with C++11]

codecvt_mode · codecvt_utf16 · codecvt_utf8 · codecvt_utf8_utf16

Include the header <codecvt> to define several template classes that describe objects based on template class codecvt. These objects can serve as locale facets that control conversions between a sequence of values of type Elem and a sequence of values of type char.

namespace std {
enum codecvt_mode;

template<class Elem, unsigned long Maxcode = 0x10ffff,
    codecvt_mode Mode = (codecvt_mode)0>
    class codecvt_utf16;
template<class Elem, unsigned long Maxcode = 0x10ffff,
    codecvt_mode Mode = (codecvt_mode)0>
    class codecvt_utf8;
template<class Elem, unsigned long Maxcode = 0x10ffff,
    codecvt_mode Mode = (codecvt_mode)0>
    class codecvt_utf8_utf16;
}  // namespace std

The locale facets declared in this header convert between several character encodings. For wide characters (stored within the program in fixed-size integers):

UCS-4 means Unicode (ISO 10646) encoded within the program as a 32-bit integer.
UCS-2 means Unicode encoded within the program as a 16-bit integer.
UTF-16 means Unicode encoded within the program as either one or two 16-bit integers. (Note that this does not meet all the requirements of a valid wide-character encoding for Standard C or Standard C++. Nevertheless it is widely used as such.)

For byte streams (stored in a file, transmitted as a byte sequence, or stored within the program in an array of char):

UTF-8 means Unicode encoded within a byte stream as one or more eight-bit bytes with a deterministic byte order.
UTF-16LE means Unicode encoded within a byte stream as UTF-16 with each 16-bit integer presented as two eight-bit bytes, less significant byte first.
UTF-16BE means Unicode encoded within a byte stream as UTF-16 with each 16-bit integer presented as two eight-bit bytes, more significant byte first.

`codecvt_mode`

namespace std {
enum codecvt_mode {
    consume_header = 4,
    generate_header = 2,
    little_endian = 1};

The enumeration defines three constants that supply configuration information to the locale facets declared in this header:

consume_header -- to consume an initial header sequence when reading a multibyte sequence and determine the endianness of the subsequent multibyte sequence to be read
generate_header -- to generate an initial header sequence when writing a multibyte sequence to advertise the endianness of the subsequent multibyte sequence to be written
little_endian -- to generate a multibyte sequence in little-endian order, as opposed to the default big-endian order

These constants can be ORed together in arbitrary combinations.

`codecvt_utf16`

template<class Elem, unsigned long Maxcode = 0x10ffff,
    codecvt_mode Mode = (codecvt_mode)0>
    class codecvt_utf16;

The locale facet converts between wide characters of type Elem, encoded as UCS-2 or UCS-4, and a byte stream encoded as UTF-16LE if Mode & little_endian or UTF-16BE otherwise. The byte stream should be written to a binary file; it can be corrupted if written to a text file.

`codecvt_utf8`

template<class Elem, unsigned long Maxcode = 0x10ffff,
    codecvt_mode Mode = (codecvt_mode)0>
    class codecvt_utf8;

The locale facet converts between wide characters of type Elem, encoded as UCS-2 or UCS-4, and a byte stream encoded as UTF-8. The byte stream can be written to either a binary file or a text file.

`codecvt_utf8_utf16`

template<class Elem, unsigned long Maxcode = 0x10ffff,
    codecvt_mode Mode = (codecvt_mode)0>
    class codecvt_utf8_utf16;

The locale facet converts between wide characters of type Elem, encoded as UTF-16, and a byte stream encoded as UTF-8. The byte stream can be written to either a binary file or a text file.

See also the Table of Contents and the Index.