Annex D (normative) Compatibility features [depr]

D.21 Deprecated standard code conversion facets [depr.locale.stdcvt]

D.21.3 Requirements [depr.locale.stdcvt.req]

1
#
For each of the three code conversion facets codecvt_­utf8, codecvt_­utf16, and codecvt_­utf8_­utf16:
  • (1.1)
    Elem is the wide-character type, such as wchar_­t, char16_­t, or char32_­t.
  • (1.2)
    Maxcode is the largest wide-character code that the facet will read or write without reporting a conversion error.
  • (1.3)
    If (Mode & consume_­header), the facet shall consume an initial header sequence, if present, when reading a multibyte sequence to determine the endianness of the subsequent multibyte sequence to be read.
  • (1.4)
    If (Mode & generate_­header), the facet shall generate an initial header sequence when writing a multibyte sequence to advertise the endianness of the subsequent multibyte sequence to be written.
  • (1.5)
    If (Mode & little_­endian), the facet shall generate a multibyte sequence in little-endian order, as opposed to the default big-endian order.
2
#
For the facet codecvt_­utf8:
  • (2.1)
    The facet shall convert between UTF-8 multibyte sequences and UCS-2 or UTF-32 (depending on the size of Elem) within the program.
  • (2.2)
    Endianness shall not affect how multibyte sequences are read or written.
  • (2.3)
    The multibyte sequences may be written as either a text or a binary file.
3
#
For the facet codecvt_­utf16:
  • (3.1)
    The facet shall convert between UTF-16 multibyte sequences and UCS-2 or UTF-32 (depending on the size of Elem) within the program.
  • (3.2)
    Multibyte sequences shall be read or written according to the Mode flag, as set out above.
  • (3.3)
    The multibyte sequences may be written only as a binary file.
    Attempting to write to a text file produces undefined behavior.
4
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For the facet codecvt_­utf8_­utf16:
  • (4.1)
    The facet shall convert between UTF-8 multibyte sequences and UTF-16 (one or two 16-bit codes) within the program.
  • (4.2)
    Endianness shall not affect how multibyte sequences are read or written.
  • (4.3)
    The multibyte sequences may be written as either a text or a binary file.
5
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The encoding forms UTF-8, UTF-16, and UTF-32 are specified in ISO/IEC 10646.
The encoding form UCS-2 is specified in ISO/IEC 10646:2003.332
332)
Cancelled and replaced by ISO/IEC 10646:2017.
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