[#BloombergLP-bdlde-CharConvertUtf16-utf8ToUtf16-079]
= xref:BloombergLP.adoc[BloombergLP]::xref:BloombergLP/bdlde.adoc[bdlde]::xref:BloombergLP/bdlde/CharConvertUtf16.adoc[CharConvertUtf16]::utf8ToUtf16
:relfileprefix: ../../../
:mrdocs:

Load into the specified `dstBuffer` of the specified `dstCapacity`, the result of converting the specified UTF‐8 `srcString` to its UTF‐16 equivalent. Optionally specify `numCodePointsWritten`, which (if not 0) indicates the location of the variable into which the number of UTF‐16 code points (including the terminating 0) written is to be loaded. Optionally specify `numWordsWritten`, which (if not 0) indicates the location of the modifiable variable into which the number of `short` _memory words_ written (including the null terminator) is to be loaded. Optionally specify an `errorWord` to be substituted (if not 0) for invalid encodings in the input string. Invalid encodings are multi‐byte encoding parts out of sequence, non‐minimal UTF‐8 encodings of code points, or code points outside the ranges that UTF‐16 can validly encode (in the range `[ 1 .. 0xd7ff ]` or `[ 0xde00 .. 0x10ffff ]`). Optionally specify `byteOrder` to indicate the byte order of the UTF‐16 output; if `byteOrder` is not specified, the output is assumed to be in host byte order. If `errorWord` is 0, invalid input sequences are ignored (i.e., produce no corresponding output). Return 0 on success and a bit‐wise or of the bits specified by `CharConvertStatus::Enum` otherwise to indicate that there were invalid sequences or if `dstCapacity` was inadequate to store the output. If `dstCapacity > 0` yet `dstCapacity` specifies a buffer too small to hold the output, the maximal null‐terminated prefix of the properly converted result string is loaded into `dstBuffer`. The behavior is undefined unless `dstBuffer`, if specified, refers to an array of at least `dstCapacity` elements, `errorWord` is either 0 or a valid single‐word encoded UTF‐16 code point (in the range `[ 1 .. 0xd7ff ]` or `[ 0xe000 .. 0xffff ]`), and `srcString` is null‐terminated if supplied as a `const char *`. Note that if `dstCapacity` is 0, `*dstBuffer` is not modified and this function returns a value with `CharConvertStatus::k_OUT_OF_SPACE_BIT` set and 0 is written into `*numCodePointsWritten` and `*numWordsWritten` (if those pointers are non‐null), since there is insufficient space for even a null terminator alone. Also note that one code point can occupy multiple 16‐bit words, so that `*numWordsWritten` may be greater than `*numCodePointsWritten`, and therefore that an input `srcString` of `dstCapacity` code points may not fit into `dstBuffer`. However, an input `srcString` of `dstCapacity` bytes (including terminating 0, if present) will always fit (since the UTF‐8 encoding of a code point requires at least as many bytes as the UTF‐16 encoding requires words). Also note that if `srcString` is a `bslstl::StringRef`, it may contain embedded null bytes that will be translated to null words embedded in the output.

== Synopsis

Declared in `<bdlde_charconvertutf16.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
static
int
utf8ToUtf16(
    char16_t* dstBuffer,
    std::size_t dstCapacity,
    std::string_view const& srcString,
    std::size_t* numCodePointsWritten = 0,
    std::size_t* numWordsWritten = 0,
    char16_t errorChar = '?',
    xref:BloombergLP/bdlde/ByteOrder/Enum.adoc[ByteOrder::Enum] byteOrder = ByteOrder::e_HOST);
----


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